A method for recycling waste ternary lithium batteries

Abstract

This paper discloses a method for recycling waste ternary lithium batteries, belonging to the field of resource recycling technology. The method can efficiently separate and recover nickel, cobalt, manganese and lithium from waste ternary lithium batteries while preparing battery-grade graphite. It has the advantages of simple process, environmental friendliness, high safety, high economic benefits, high production efficiency and high recovery rate, and has broad application prospects.

Description

Technical Field

[0001] This article relates to the field of resource recycling technology, specifically a method for recycling waste ternary lithium batteries. Background Technology

[0002] Discarded lithium-ion batteries typically contain large amounts of harmful organic pollutants and heavy metal inorganic compounds. Improper disposal of these wastes poses a serious threat to human health, the environment, and biodiversity. Heavy metals and negative electrode graphite from discarded batteries have recycling value; they can be reused in the manufacture of new energy materials, reducing environmental pollution and generating significant economic benefits. Discarded ternary lithium-ion batteries contain large amounts of valuable metals such as nickel, cobalt, manganese, and lithium; recycling them is beneficial for environmental protection and improving economic efficiency. Furthermore, with the continuous depletion of natural graphite resources and the rapid increase in the price of artificial graphite, the effective recycling of negative electrode graphite from discarded batteries can not only address resource shortages but also solve environmental pollution problems.

[0003] Currently, the main industrial processes for recycling valuable metals from waste batteries are: ① Under normal pressure, using sulfuric acid and hydrogen peroxide to leach nickel, cobalt, manganese, and lithium from the battery powder as nickel sulfate, cobalt sulfate, manganese sulfate, and lithium sulfate, respectively. This method introduces the risk of overflow during production due to the addition of hydrogen peroxide, and increases risk control costs. Furthermore, hydrogen peroxide is a consumable and easily decomposes at high temperatures, resulting in low utilization and increased production costs. ② A low-acid combined with high-pressure leaching process. This method fails to consider two safety hazards. Firstly, battery powder inevitably contains fluorine compounds, originating from lithium hexafluorophosphate in the electrolyte or PVDF in the separator. During high-pressure acid leaching, fluorine reacts with hydrogen ions to form hydrofluoric acid, a highly corrosive acid that corrodes the autoclave, creating safety hazards and increasing subsequent maintenance costs. Secondly, battery powder may also contain aluminum foil and other substances. If the elemental metals are not treated before high-pressure leaching, they will react with acid during the process to generate hydrogen gas, posing an explosion risk. Alternatively, the leaching residue containing carbon powder may be disposed of as waste, failing to recover the negative electrode carbon powder from the leaching residue. This not only wastes graphite resources but also harms environmental health. Furthermore, the nickel sulfate, cobalt sulfate, manganese sulfate, and lithium sulfate obtained from these methods require subsequent extraction processes for further separation and purification. Extraction technology is widely used in waste battery recycling, but it is costly, and the treatment of oily and organic waste liquids is quite difficult, which undoubtedly greatly increases production costs.

[0004] CN112176191A discloses a method for recovering valuable metals from waste lithium-ion batteries. This method involves a pre-leaching stage after low-acid leaching, followed by high-pressure leaching of the pre-leached residue. However, the low acid concentration and short leaching time in this method make it difficult to completely remove fluorine and residual elemental aluminum from the low-acid residue. Residual fluorine in the pre-leached residue can corrode high-pressure equipment, increasing safety hazards. Furthermore, residual elemental aluminum in the pre-leached residue can react with acid during high-pressure leaching to generate hydrogen gas, increasing the risk of explosion and severely impacting the on-site safe operating environment. Simultaneously, the entire leaching process struggles to effectively reduce and recover cobalt and manganese, resulting in a low recovery rate of valuable metals.

[0005] CN108987841A discloses a method for recovering valuable metals from waste lithium-ion batteries. This method involves low-acid, atmospheric-pressure leaching to obtain low-acid slag, followed by high-pressure leaching of the slag. However, this method struggles to remove fluoride in low-acid conditions, leading to fluoride-containing slag entering the high-pressure reactor. This causes corrosion of the reactor during high-pressure leaching, increasing safety hazards and subsequent maintenance costs. Furthermore, the recovery rate of valuable metals is low, and the leaching residue contains a high amount of residual metals, making it unsuitable for direct use as battery-grade graphite raw material. Additionally, the addition of hydrogen peroxide as a reducing agent during leaching frequently results in overflow, increasing the hazardous environment during on-site operations. Moreover, hydrogen peroxide is a consumable that is easily decomposed at high temperatures, leading to low utilization and increased production costs.

[0006] In existing technologies, the leachate used in the recycling of waste lithium-ion batteries is a mixed solution of nickel, cobalt, and manganese sulfate. Subsequent extraction is required to separate nickel, cobalt, and manganese, which cannot effectively separate nickel, cobalt, and manganese.

[0007] Therefore, this paper is presented. Summary of the Invention

[0008] The purpose of this paper is to overcome the shortcomings of existing technologies and provide a method for recycling waste ternary lithium batteries. The method described in this paper can efficiently separate and recover nickel, cobalt, manganese and lithium from waste ternary lithium batteries while preparing battery-grade graphite. It has the advantages of simple process, environmental friendliness, high safety, high economic benefits, high production efficiency and high recovery rate, and has broad application prospects.

[0009] To achieve the above objectives, the technical solution adopted in this paper is as follows:

[0010] A method for recycling used ternary lithium batteries includes the following steps:

[0011] Waste ternary lithium battery powder, manganese sulfide, and first sulfuric acid solution are mixed evenly and then roasted for the first time to obtain a first roasted material. The first roasted material is then soaked in water to obtain a lithium sulfate solution and a water-soaked residue.

[0012] The water leaching residue is mixed with the second sulfuric acid solution, and ozone is introduced for high-pressure leaching to obtain a nickel sulfate solution and a primary high-pressure leaching residue.

[0013] The primary high-pressure leaching residue is mixed with the third sulfuric acid solution, and sulfur dioxide and oxygen are successively introduced for high-pressure leaching to obtain cobalt sulfate solution and secondary high-pressure leaching residue.

[0014] The residue from the secondary high-pressure leaching process is then roasted a second time to obtain the secondary roasted material.

[0015] The secondary roasting material, sodium sulfide and fourth sulfuric acid solution are mixed and acid-leached to obtain manganese sulfate solution and first acid residue;

[0016] The first acid residue was mixed with the fifth sulfuric acid solution and leached to obtain graphite and acid solution.

[0017] This paper creatively incorporates manganese sulfide ore into the roasting of waste battery powder. In the presence of manganese sulfide, the difficult-to-leach high-valence cobalt and manganese in the waste battery powder can be reduced to easily leached low-valence metal oxides. After water leaching, a lithium sulfate solution is obtained. The added manganese is then discharged in the form of manganese sulfate solution in subsequent stages, reducing the need for other reducing agents and reducing auxiliary material costs. After the waste ternary lithium battery powder, manganese sulfide, and the first sulfuric acid solution are mixed and roasted, fluorine in the residue can be removed, avoiding corrosion damage to the autoclave by fluorine during high-pressure leaching and improving the safety factor of the high-pressure equipment. In the presence of ozone, the cobalt and manganese leached in the solution are oxidized into difficult-to-leach high-valence oxides, effectively separating nickel sulfate from cobalt and manganese to obtain a nickel sulfate solution. The residue from the first high-pressure leaching stage is then subjected to a second high-pressure leaching stage, and in the presence of sulfur dioxide and oxygen, cobalt and manganese are effectively separated to obtain a cobalt sulfate solution. The final two stages of high-pressure leaching residue are roasted at high temperature under inert gas. In the presence of carbon powder in the battery powder, high-valence manganese is reduced to easily leached low-valence manganese, which is then leached with sulfuric acid to become manganese sulfate. The entire process eliminates the cobalt and manganese extraction stage, reducing cost input.

[0018] The method presented in this paper can efficiently separate and recycle nickel, cobalt, manganese, and lithium from waste ternary lithium batteries while preparing battery-grade graphite. It has the advantages of simple process, environmental friendliness, high safety, high economic benefits, high production efficiency, and high recovery rate. It has great improvement over the shortcomings of existing technologies and has promising prospects for industrial application.

[0019] This article describes a roasting process involving the addition of manganese sulfate ore, a small amount of sulfuric acid, and waste battery powder, primarily serving two purposes:

[0020] (1) Sulfur manganese ore reduces lithium nickel cobalt manganese oxide in waste battery powder to lithium sulfate and nickel oxide, cobalt oxide and manganese oxide. The reaction mechanism is as follows:

[0021] 2MnS + O2 → 2MnO + S

[0022] 2MnS + 3O2 → 2MnO + 2SO2

[0023] 2(LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2) + 3S → Li2SO4 + 2Ni 1 / 3 Co 1 / 3 Mn 1 / 3 S

[0024] 2(LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2) + 3SO2 + O2 → Li2SO4 + 2Ni 1 / 3 Co 1 / 3 Mn 1 / 3 SO4

[0025] NiSO4 → NiO + SO2 + 1 / 2O2

[0026] CoSO4 → 1 / 3Co3O4 + SO2 + 1 / 3O2

[0027] MnSO4 → 1 / 3Mn3O4 + SO2 + 1 / 3O2

[0028] (2) On the other hand, sulfuric acid converts the fluorides in the waste battery powder into hydrogen fluoride. At high temperature, the hydrogen fluoride gas is released from the waste battery powder, thus avoiding the formation of hydrogen fluoride during the high-pressure leaching process, which would lead to corrosion and damage to the autoclave. The reaction mechanism is as follows:

[0029] LiPF6→LiF+PF5(g)

[0030] LiF+1 / 2H2SO4→1 / 2Li2SO4+HF(g)

[0031] This paper describes a two-stage high-pressure leaching process that effectively separates nickel, cobalt, and manganese into nickel sulfate, cobalt sulfate, and manganese sulfate solutions, eliminating the need for an extraction stage and significantly reducing production costs.

[0032] (1) Under high-pressure leaching, ozone exhibits extremely strong oxidizing properties, which can oxidize easily leached low-valence cobalt and manganese oxides into difficult-to-leach high-valence oxides, thereby effectively separating nickel from cobalt and manganese. The reaction mechanism is as follows:

[0033] 6CoO + 3MnO + 2O3 → 3Co2O3 + 3MnO2

[0034] (2) The two-stage high-pressure sulfur dioxide / oxygen mixing method can effectively separate cobalt and manganese, because Co 3+ +e→Co 2+The standard potential is 1.8V, while MnO2 + 4H+ + +2e→Mn 2+ The standard potential of H₂O is 1.23V, and the potential difference between the two is relatively large. This paper controls the addition ratio and parameters to make Mn 2+ Priority over Co 2+ Cobalt and manganese can be separated by the preferential oxidation and precipitation of manganese to form MnO2 precipitate.

[0035] In one embodiment, the molar concentration of the first sulfuric acid solution is 0.2 to 0.5 mol / L, and the molar concentrations of the second and third sulfuric acid solutions are each independently 3 to 5 mol / L.

[0036] In one embodiment, the mass concentrations of the fourth sulfuric acid solution and the fifth sulfuric acid solution are each independently 150–250 g / L.

[0037] In one embodiment, the mass ratio of the waste ternary lithium battery powder to manganese sulfide is 1:(0.5-1.2).

[0038] In one embodiment, the liquid-to-solid ratio of the first sulfuric acid solution to the waste ternary lithium battery powder is (0.2-0.5) mL: 1 g.

[0039] In one embodiment, the temperature of the first calcination is 700–1000°C, and the calcination time is 1–4 hours.

[0040] In one embodiment, the temperature of the second roasting is 500-900°C, and the roasting time is 1-4 hours.

[0041] In one embodiment, the secondary high-pressure leaching residue is subjected to a second roasting under a sulfur dioxide atmosphere.

[0042] In one embodiment, when the primary calcined material is soaked in water, the solid-liquid ratio of the primary calcined material to water is 1g:(2-5)mL, the soaking time is 3-7h, and the soaking temperature is 60-90℃.

[0043] In one embodiment, the solid-liquid ratio of the water-leached residue to the second sulfuric acid solution is 1 g: (3-8) mL.

[0044] In one embodiment, the solid-liquid ratio of the primary high-pressure leaching residue to the third sulfuric acid solution is 1 g: (4-8) mL.

[0045] In one embodiment, when ozone is introduced for high-pressure leaching, the temperature is 110–200°C, the partial pressure of ozone is 0.2–0.6 MPa, and the high-pressure leaching time is 3–8 hours.

[0046] In one embodiment, when sulfur dioxide and oxygen are introduced sequentially for high-pressure leaching, the temperature is 110-200°C, the sulfur dioxide is introduced for 2-4 hours, the partial pressure of sulfur dioxide is 0.1-0.5 MPa, the oxygen is introduced for 2-4 hours, and the partial pressure of oxygen is 0.2-0.6 MPa.

[0047] In one embodiment, the ratio of the secondary roasting material, sodium sulfide, and fourth sulfuric acid solution is 1g:(0.05-0.15)g:(2-5)mL.

[0048] In one embodiment, the solid-liquid ratio of the first acid residue to the fifth sulfuric acid solution is 1 g: (2-4) mL.

[0049] In one embodiment, when the secondary roasted material, sodium sulfide and fourth sulfuric acid solution are mixed and acid-leached, the temperature is 60-90°C and the time is 3-7 hours.

[0050] In one embodiment, when the first acid residue is mixed with the fifth sulfuric acid solution for acid leaching, the temperature is 60-90°C and the time is 2-5 hours.

[0051] The beneficial effects of this paper are as follows: This paper uses manganese sulfide ore to roast waste battery powder. In the presence of manganese sulfide, the difficult-to-leach high-valence cobalt and manganese in the waste battery powder can be reduced to easily leached low-valence metal oxides. After water leaching, a lithium sulfate solution is obtained. The added manganese is then discharged in the form of manganese sulfate solution in subsequent stages, reducing the need for other reducing agents and reducing auxiliary material costs. After roasting the waste ternary lithium battery powder, manganese sulfide, and the first sulfuric acid solution, fluorine in the residue can be removed, avoiding corrosion damage to the autoclave by fluorine during high-pressure leaching and improving the safety factor of the high-pressure equipment. Furthermore, in the presence of ozone, the cobalt and manganese leached in the solution are oxidized into difficult-to-leach high-valence oxides, effectively separating nickel sulfate from cobalt and manganese to obtain a nickel sulfate solution. The residue from the first high-pressure leaching stage undergoes a second high-pressure leaching stage, and under the combined atmosphere of sulfur dioxide and oxygen, cobalt and manganese are effectively separated to obtain a cobalt sulfate solution. The final two stages of high-pressure leaching residue are roasted at high temperature under sulfur dioxide gas. In the presence of carbon powder in the battery powder, high-valence manganese is reduced to easily leached low-valence manganese, which is then leached with sulfuric acid to become manganese sulfate. The entire process eliminates the cobalt and manganese extraction stage, reducing cost input. Detailed Implementation

[0052] To better illustrate the purpose, technical solutions, and advantages of this document, the following detailed description, in conjunction with specific embodiments and comparative examples, is intended to provide a thorough understanding of the content of this document, rather than to limit it.

[0053] Unless otherwise specified, all components and raw materials used in the embodiments and comparative examples in this article are commercially available, and the same components and raw materials are used in each parallel experiment.

[0054] Example 1

[0055] A method for recycling used ternary lithium batteries includes the following steps:

[0056] (1) Mix 1 kg of waste ternary lithium battery powder (with nickel, cobalt, manganese and lithium contents of 26.5%, 4.3%, 4.0% and 3.5% respectively), 800 g of manganese sulfide and 400 mL of 0.4 mol / L sulfuric acid solution evenly. Put the mixed slurry into a roasting furnace and roast at 900 °C for 3 h in air atmosphere. After roasting, the F content of the first roasted material is 0.0001 wt%.

[0057] (2) Mix the first-calcined material with water at a solid-liquid ratio of 1g:3mL, soak in water at 80℃ for 5h, filter, and obtain lithium sulfate solution and water-leached residue;

[0058] (3) The water leaching residue and 4 mol / L sulfuric acid solution were mixed at a solid-liquid ratio of 1 g: 4 mL and placed in a high pressure vessel. Ozone was introduced and the partial pressure of ozone was 0.5 MPa. The mixture was leached at 160 °C for 4 h. After filtration, nickel sulfate solution and first high pressure leaching residue were obtained.

[0059] (4) The residue from the first high-pressure leaching was mixed with a 4 mol / L sulfuric acid solution at a solid-liquid ratio of 1 g: 5 mL and placed in a high-pressure vessel. Sulfur dioxide was introduced, with a partial pressure of 0.4 MPa, and the mixture was leached at 150 °C for 1 h. Then oxygen was introduced, with a partial pressure of 0.5 MPa, and the mixture was leached at 150 °C for 4 h. The mixture was then filtered to obtain a cobalt sulfate solution and a residue from the second high-pressure leaching.

[0060] (5) The secondary high-pressure leaching residue is placed in a roasting furnace and roasted at 900°C for 3 hours under a sulfur dioxide atmosphere to obtain secondary roasted material;

[0061] (6) After mixing the secondary roasting material, sodium sulfide and 200 g / L sulfuric acid solution evenly, the mixture is acid-leached at 80 °C for 3 h to obtain manganese sulfate solution and first acid-soluble residue; the ratio of secondary roasting material, sodium sulfide and sulfuric acid solution is 1 g: 0.05 g: 4 mL.

[0062] (7) After mixing the first acid residue with 200 g / L sulfuric acid solution evenly, the ratio of the first acid residue to sulfuric acid solution is 1 g: 2 mL. The mixture is then acid-leached at 60 °C for 3 h to obtain battery-grade graphite and acid solution. The acid solution can be recycled and reused.

[0063] The residual metal content of the graphite was as follows: Ni 0.0025 wt.%, Co 0.0001 wt.%, Mn 0.0021 wt.%, and Li 0.0008 wt.%.

[0064] The leachate at each stage is shown in Table 1.

[0065] Table 1

[0066] element Li Ni Co Mn Lithium sulfate solution, g / L 12.56 0.0021 0.0008 0.0011 Nickel sulfate solution, g / L 0.0001 89.71 0.0017 0.0009 Cobalt sulfate solution, g / L 0.0001 0.0001 22.36 0.0034 Manganese sulfate solution, g / L 0.0001 0.0001 0.0001 118.11 Recovery rate, % 99.95 99.94 99.98 99.99

[0067] Example 2

[0068] A method for recycling used ternary lithium batteries includes the following steps:

[0069] (1) Mix 1 kg of waste ternary lithium battery powder (with nickel, cobalt, manganese and lithium contents of 26.5%, 4.3%, 4.0% and 3.5% respectively), 500 g of manganese sulfide and 500 mL of 0.2 mol / L sulfuric acid solution evenly. Put the mixed slurry into a roasting furnace and roast at 700°C for 4 h in air atmosphere. After roasting, the F content of the first roasted material is 0.0003 wt%.

[0070] (2) Mix the first-calcined material with water at a solid-liquid ratio of 1g:2mL, soak in water at 90℃ for 5h, filter, and obtain lithium sulfate solution and water-leached residue;

[0071] (3) The water leaching residue and 3 mol / L sulfuric acid solution were mixed at a solid-liquid ratio of 1 g: 5 mL and placed in a high pressure vessel. Ozone was introduced and the partial pressure of ozone was 0.4 MPa. The mixture was leached at 180°C for 5 h. After filtration, nickel sulfate solution and first high pressure leaching residue were obtained.

[0072] (4) The residue from the first high-pressure leaching was mixed with 4 mol / L sulfuric acid solution at a solid-liquid ratio of 1 g: 3 mL and placed in a high-pressure vessel. Sulfur dioxide was introduced and the partial pressure of sulfur dioxide was 0.5 MPa. The mixture was leached at 170 °C for 2 h. Then oxygen was introduced and the partial pressure of oxygen was 0.6 MPa. The mixture was leached at 170 °C for 3 h. The mixture was filtered to obtain cobalt sulfate solution and residue from the second high-pressure leaching.

[0073] (5) The secondary high-pressure leaching residue is placed in a roasting furnace and roasted at 700°C for 3 hours under a sulfur dioxide atmosphere to obtain secondary roasted material;

[0074] (6) After mixing the secondary roasting material, sodium sulfide and 200 g / L sulfuric acid solution evenly, the mixture is acid-leached at 70 °C for 6 h to obtain manganese sulfate solution and first acid-soluble residue; the ratio of secondary roasting material, sodium sulfide and sulfuric acid solution is 1 g: 0.1 g: 3 mL.

[0075] (7) After mixing the first acid slag with 200 g / L sulfuric acid solution evenly, the mixture is acid-leached at 70°C for 4 h to obtain battery-grade graphite and acid solution. The ratio of the first acid slag to sulfuric acid solution is 1 g: 3 mL, and the acid solution can be recycled and reused.

[0076] The residual metal content of the graphite was as follows: Ni 0.0005 wt.%, Co 0.0011 wt.%, Mn 0.0016 wt.%, and Li 0.0005 wt.%.

[0077] The leachate at each stage is shown in Table 2.

[0078] Table 2

[0079] element Li Ni Co Mn Lithium sulfate solution, g / L 16.65 0.0011 0.0010 0.0006 Nickel sulfate solution, g / L 0.0001 71.39 0.0027 0.0011 Cobalt sulfate solution, g / L 0.0001 0.0001 36.35 0.0034 Manganese sulfate solution, g / L 0.0001 0.0001 0.0001 101.37 Recovery rate, % 99.96 99.95 99.96 99.98

[0080] Example 3

[0081] A method for recycling used ternary lithium batteries includes the following steps:

[0082] (1) Mix 1 kg of waste ternary lithium battery powder (with nickel, cobalt, manganese and lithium contents of 26.5%, 4.3%, 4.0% and 3.5% respectively), 1200 g of manganese sulfide and 300 mL of 0.5 mol / L sulfuric acid solution evenly. Put the mixed slurry into a roasting furnace and roast it at 1000 °C for 1 h in air atmosphere. After roasting, the F content of the first roasted material is 0.0002 wt%.

[0083] (2) Mix the first-calcined material with water at a solid-liquid ratio of 1g:5mL, soak in water at 70℃ for 5h, filter, and obtain lithium sulfate solution and water-leached residue;

[0084] (3) The water leaching residue and 5 mol / L sulfuric acid solution were mixed at a solid-liquid ratio of 1 g: 8 mL and placed in a high pressure vessel. Ozone was introduced and the partial pressure of ozone was 0.45 MPa. The mixture was leached at 190 °C for 4 h. After filtration, nickel sulfate solution and first high pressure leaching residue were obtained.

[0085] (4) The residue from the first high-pressure leaching was mixed with a 4 mol / L sulfuric acid solution at a solid-liquid ratio of 1 g: 5 mL and placed in a high-pressure vessel. Sulfur dioxide was introduced, with a partial pressure of 0.4 MPa, and the mixture was leached at 170 °C for 2 h. Then oxygen was introduced, with a partial pressure of 0.5 MPa, and the mixture was leached at 170 °C for 3 h. The mixture was then filtered to obtain a cobalt sulfate solution and a residue from the second high-pressure leaching.

[0086] (5) The secondary high-pressure leaching residue is placed in a roasting furnace and roasted at 600°C for 3 hours under a sulfur dioxide atmosphere to obtain secondary roasted material;

[0087] (6) After mixing the secondary roasting material, sodium sulfide and 200 g / L sulfuric acid solution evenly, the mixture is acid-leached at 60°C for 6 h to obtain manganese sulfate solution and first acid-soluble residue; the ratio of secondary roasting material, sodium sulfide and sulfuric acid solution is 1 g: 0.15 g: 5 mL.

[0088] (7) After mixing the first acid residue with 200 g / L sulfuric acid solution evenly, the ratio of the first acid residue to sulfuric acid solution is 1 g: 4 mL. The mixture is then acid-leached at 70 °C for 4 h to obtain battery-grade graphite and acid solution. The acid solution can be recycled and reused.

[0089] The residual metal content of the graphite was as follows: Ni 0.0005 wt.%, Co 0.0011 wt.%, Mn 0.0016 wt.%, and Li 0.0005 wt.%.

[0090] The leachate at each stage is shown in Table 3.

[0091] Table 3

[0092] element Li Ni Co Mn Lithium sulfate solution, g / L 10.65 0.0011 0.0010 0.0006 Nickel sulfate solution, g / L 0.0001 60.39 0.0027 0.0011 Cobalt sulfate solution, g / L 0.0001 0.0001 21.35 0.0034 Manganese sulfate solution, g / L 0.0001 0.0001 0.0001 135.37 Recovery rate, % 99.96 99.95 99.96 99.98

[0093] Comparative Example 1

[0094] The difference between Comparative Example 1 and Example 1 is that no manganese sulfide was added in Comparative Example 1, but everything else is the same.

[0095] A method for recycling used ternary lithium batteries includes the following steps:

[0096] (1) Mix 1 kg of waste ternary lithium battery powder (with nickel, cobalt, manganese and lithium contents of 26.5%, 4.3%, 4.0% and 3.5% respectively) and 400 mL of 0.4 mol / L sulfuric acid solution evenly. Put the mixed slurry into a roasting furnace and roast it at 900°C for 3 hours in air atmosphere. After roasting, the F content of the first roasted material is 0.0009 wt%.

[0097] (2) Mix the first-calcined material with water at a solid-liquid ratio of 1g:3mL, soak in water at 80℃ for 5h, filter, and obtain lithium sulfate solution and water-leached residue;

[0098] (3) The water leaching residue and 4 mol / L sulfuric acid solution were mixed at a solid-liquid ratio of 1 g: 4 mL and placed in a high pressure vessel. Ozone was introduced and the partial pressure of ozone was 0.5 MPa. The mixture was leached at 160 °C for 4 h. After filtration, nickel sulfate solution and first high pressure leaching residue were obtained.

[0099] (4) The residue from the first high-pressure leaching was mixed with a 4 mol / L sulfuric acid solution at a solid-liquid ratio of 1 g: 5 mL and placed in a high-pressure vessel. Sulfur dioxide was introduced, with a partial pressure of 0.4 MPa, and the mixture was leached at 150 °C for 1 h. Then oxygen was introduced, with a partial pressure of 0.5 MPa, and the mixture was leached at 150 °C for 4 h. The mixture was then filtered to obtain a cobalt sulfate solution and a residue from the second high-pressure leaching.

[0100] (5) The secondary high-pressure leaching residue is placed in a roasting furnace and roasted at 900°C for 3 hours under a sulfur dioxide atmosphere to obtain secondary roasted material;

[0101] (6) After mixing the secondary roasting material, sodium sulfide and 200 g / L sulfuric acid solution evenly, the mixture is acid-leached at 80 °C for 3 h to obtain manganese sulfate solution and first acid-soluble residue; the ratio of secondary roasting material, sodium sulfide and sulfuric acid solution is 1 g: 0.05 g: 4 mL.

[0102] (7) After mixing the first acid residue with 200 g / L sulfuric acid solution evenly, the ratio of the first acid residue to sulfuric acid solution is 1 g: 2 mL. The mixture is then acid-leached at 60 °C for 3 h to obtain battery-grade graphite and acid solution. The acid solution can be recycled and reused.

[0103] The residual metal content of the graphite was as follows: Ni 0.1127 wt.%, Co 0.1037 wt.%, Mn 0.0967 wt.%, and Li 0.0009 wt.%.

[0104] The leachate at each stage is shown in Table 4.

[0105] Table 4

[0106] element Li Ni Co Mn Lithium sulfate solution, g / L 0.005 0.0009 0.0008 0.0002 Nickel sulfate solution, g / L 9.23 60.68 0.0011 0.0007 Cobalt sulfate solution, g / L 2.36 16.37 21.95 0.0010 Manganese sulfate solution, g / L 0.0006 0.0013 0.0009 15.97 Recovery rate, % 99.69％ 98.96％ 97.66％ 98.98％

[0107] Comparative Example 2

[0108] The difference between Comparative Example 2 and Example 1 is that ozone was not introduced in step (3) of Comparative Example 2, but everything else is the same.

[0109] The residual metal content of the graphite in this comparative example was as follows: Ni 0.0034 wt.%, Co 0.0006 wt.%, Mn 0.0007 wt.%, and Li 0.0006 wt.%.

[0110] The leachate at each stage is shown in Table 5.

[0111] Table 5

[0112]

[0113]

[0114] Comparative Example 3

[0115] The difference between Comparative Example 3 and Example 1 is that sulfur dioxide was not introduced in step (4) of Comparative Example 3, but everything else is the same.

[0116] The residual metal detection results of the graphite in this comparative example are: Ni 0.0019 wt.%, Co 0.0031 wt.%, Mn 0.0011 wt.%, and Li 0.0008 wt.%.

[0117] The leachate at each stage is shown in Table 6.

[0118] Table 6

[0119] element Li Ni Co Mn Lithium sulfate solution, g / L 12.61 0.0011 0.0009 0.0009 Nickel sulfate solution, g / L 0.0001 90.31 0.0021 0.0011 Cobalt sulfate solution, g / L 0.0001 0.0001 0.046 0.0937 Manganese sulfate solution, g / L 0.0001 0.0001 25.67 119.36 Recovery rate, % 99.93 99.91 98.98 99.89

[0120] Comparative Example 4

[0121] The difference between Comparative Example 4 and Example 1 is that oxygen was not introduced in step (4) of Comparative Example 4, but everything else is the same.

[0122] The residual metal detection results of the graphite in this comparative example are: Ni 0.0015 wt.%, Co 0.0011 wt.%, Mn 0.0021 wt.%, and Li 0.0009 wt.%.

[0123] The leachate at each stage is shown in Table 7.

[0124] Table 7

[0125]

[0126]

[0127] As can be seen from Examples 1-3 and Comparative Examples 1-4, the method described in this paper can efficiently separate and recover nickel, cobalt, manganese, and lithium from waste ternary lithium batteries while preparing battery-grade graphite. A comparison between Example 1 and Comparative Example 1 shows that the addition of manganese sulfide reduces the high-valence metals in the ternary lithium battery, thereby disrupting the stable structure of lithium nickel cobalt manganese oxide. The addition of manganese sulfide reduces the residual metal content in the graphite, achieving efficient separation and recovery of nickel, cobalt, manganese, and lithium from waste ternary lithium batteries.

[0128] As can be seen from the comparison between Example 1 and Comparative Example 2, this paper introduces ozone during a single high-pressure leaching process to effectively separate nickel from cobalt and manganese, thus achieving efficient separation and recycling of nickel, cobalt, manganese, and lithium from waste ternary lithium batteries.

[0129] As can be seen from the comparison between Example 1 and Comparative Examples 3 and 4, the introduction of sulfur dioxide and oxygen during the secondary high-pressure leaching effectively reduces the cobalt and manganese oxidized to high valence states in the previous steps, effectively leaching the cobalt, and utilizing the potential difference between cobalt and manganese to oxidize only manganese to achieve effective separation of cobalt and manganese.

Claims

1. A method for recycling waste ternary lithium batteries, characterized in that, Includes the following steps: Waste ternary lithium battery powder, manganese sulfide, and first sulfuric acid solution are mixed evenly and then roasted for the first time to obtain a first roasted material. The first roasted material is then soaked in water to obtain a lithium sulfate solution and water-soaked residue. The water leaching residue is mixed with the second sulfuric acid solution, and ozone is introduced for high-pressure leaching to obtain a nickel sulfate solution and a primary high-pressure leaching residue. The primary high-pressure leaching residue is mixed with the third sulfuric acid solution, and sulfur dioxide and oxygen are successively introduced for high-pressure leaching to obtain cobalt sulfate solution and secondary high-pressure leaching residue. The residue from the secondary high-pressure leaching process is then roasted a second time to obtain the secondary roasted material. The secondary roasting material, sodium sulfide and fourth sulfuric acid solution are mixed and acid-leached to obtain manganese sulfate solution and first acid residue; The first acid residue was mixed with the fifth sulfuric acid solution and leached to obtain graphite and acid solution; When ozone is introduced for high-pressure leaching, the partial pressure of ozone is 0.2~0.6MPa; When sulfur dioxide and oxygen are introduced sequentially for high-pressure leaching, the partial pressure of sulfur dioxide is 0.1~0.5 MPa and the partial pressure of oxygen is 0.2~0.6 MPa.

2. The method for recycling waste ternary lithium batteries according to claim 1, characterized in that, The molar concentration of the first sulfuric acid solution is 0.2~0.5 mol / L, and the molar concentrations of the second and third sulfuric acid solutions are each independently 3~5 mol / L; and / or The mass concentrations of the fourth and fifth sulfuric acid solutions are each 150~250 g / L.

3. The method for recycling waste ternary lithium batteries according to claim 1, characterized in that, The mass ratio of the waste ternary lithium battery powder to manganese sulfide is 1:(0.5~1.2); and / or The liquid-to-solid ratio of the first sulfuric acid solution to the waste ternary lithium battery powder is (0.2~0.5) mL:1g.

4. The method for recycling waste ternary lithium batteries according to claim 1, characterized in that, The first roasting temperature is 700~1000℃, and the roasting time is 1~4h; and / or The second roasting temperature is 500~900℃, and the roasting time is 1~4h.

5. The method for recycling waste ternary lithium batteries according to claim 1, characterized in that, When soaking the primary roasted material in water, the solid-liquid ratio of the primary roasted material to water is 1g:(2~5)mL, the soaking time is 3~7h, and the soaking temperature is 60~90℃.

6. The method for recycling waste ternary lithium batteries according to claim 1, characterized in that, The solid-liquid ratio of the water-leached residue to the second sulfuric acid solution is 1 g: (3~8) mL; and / or The solid-liquid ratio of the first high-pressure leaching residue to the third sulfuric acid solution is 1 g: (4~8) mL.

7. The method for recycling waste ternary lithium batteries according to claim 1, characterized in that, When ozone is introduced for high-pressure leaching, the temperature is 110~200℃ and the high-pressure leaching time is 3~8h.

8. The method for recycling waste ternary lithium batteries according to claim 1, characterized in that, When sulfur dioxide and oxygen are introduced sequentially for high-pressure leaching, the temperature is 110~200℃, the sulfur dioxide is introduced for 2~4 hours, and the oxygen is introduced for 2~4 hours.

9. The method for recycling waste ternary lithium batteries according to claim 1, characterized in that, The ratio of the secondary roasting material, sodium sulfide, and quaternary sulfuric acid solution is 1g:(0.05~0.15)g:(2~5)mL; and / or The solid-liquid ratio of the first acid residue to the fifth sulfuric acid solution is 1 g: (2~4) mL.

10. The method for recycling waste ternary lithium batteries according to claim 1, characterized in that, When acid-leaching the secondary roasted material, sodium sulfide, and tetrasulfuric acid solution, the temperature is 60-90℃ and the time is 3-7 hours; and / or When the first acid residue is mixed with the fifth sulfuric acid solution for acid leaching, the temperature is 60~90℃ and the time is 2~5h.

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