Green recovery method of waste battery positive electrode material

Abstract

The invention belongs to the technical field of battery recovery, and relates to a green recovery method of a waste battery positive electrode material, which comprises the following steps: mixing a positive electrode active material separated by disassembling a waste battery with an alkali metal compound solution, adding the mixture into a high-pressure reaction kettle for reaction, and carrying out solid-liquid separation to obtain a solid and a lithium-containing filtrate; adjusting the pH value of the lithium-containing filtrate, and then carrying out solid-liquid separation to obtain filter residues and filtrate; purifying the filtrate through ion exchange resin to obtain a purified solution; carrying out lithium precipitation reaction on the purified liquid and alkali carbonate, and carrying out solid-liquid separation to obtain lithium carbonate solid; and mixing the solid lithium carbonate, introducing carbon dioxide to perform carbonization reaction, and heating the filtrate obtained by solid-liquid separation to separate out the solid, thereby obtaining the battery-grade lithium carbonate. According to the invention, sodium salt or sylvite and the like are adopted to recover the positive electrode active material of the waste lithium battery under the conditions of high pressure and high temperature, and the lithium recovery efficiency is very high.

Description

Technical Field

[0001] The invention belongs to the technical field of battery recycling and relates to a green recycling method for positive electrode materials of waste batteries. Background Art

[0002] The new energy vehicle industry has developed rapidly, and sales have continued to grow. However, with the large-scale popularization of new energy vehicles, the number of retired batteries has also increased. In 2023, global new energy vehicle sales reached 14.653 million units, a year-on-year increase of 35.4%, of which China's new energy vehicle sales reached 9.495 million units, accounting for 64.8% of global sales. It is estimated that by 2025, the total amount of retired power batteries in China will reach 116GWh, about 780,000 tons. If these waste batteries are not handled properly, they will be extremely harmful. Batteries contain heavy metals such as nickel, cobalt, and manganese, as well as harmful substances such as electrolytes. Once they are discarded at will or disassembled improperly, heavy metals will seep into the soil and water sources, causing long-term environmental pollution, affecting the ecological balance and crop growth. For example, a 20-gram mobile phone battery can pollute 1 square kilometer of land for up to 50 years, while the power batteries of new energy vehicles are larger in size, contain more heavy metals, and are more harmful. At the same time, in the process of unprofessional handling, the battery may have safety accidents such as short circuit, fire, or even explosion, posing a serious threat to the safety of life and property. Therefore, the disposal of waste batteries from new energy vehicles needs to be solved urgently, and a complete recycling system and treatment technology need to be established to achieve effective utilization of resources and environmental protection.

[0003] At present, the recycling process of waste lithium batteries is mainly based on pyrometallurgical and hydrometallurgical recycling technologies. The pyrometallurgical method mainly recovers or refines valuable metals from waste lithium-ion batteries by physical or chemical conversion at high temperature. The smelting temperature usually reaches about 800°C or above, and the products obtained are mostly alloys, such as nickel-cobalt alloys, iron alloys, etc. In this high-temperature environment, lithium mainly enters the slag phase and requires subsequent treatment to recover, resulting in a relatively low lithium recovery rate and high cost. There are also problems such as high energy consumption for high-temperature smelting, high equipment requirements, and large environmental impact of tail gas. For example, Chinese patent CN118610631A discloses a method for recycling positive electrode materials of waste lithium batteries, wherein the separated positive electrode active materials are roasted to remove impurities; then, according to the ratio of elements contained in the target positive electrode material, the required amount of lithium source, aluminum hydroxide oxide and the positive electrode active material after impurities are mixed, and the obtained mixture is roasted to obtain a repaired positive electrode material.

[0004] Wet recovery technology is a mainstream method in the field of metal recovery. The advantages of this technology include relatively mild reaction conditions, low tail gas emissions and high metal recovery rate. It mainly includes key processes such as leaching, separation and purification. In the leaching process, it is usually necessary to select a suitable leaching agent, such as sulfuric acid, sodium hydroxide, salt solution, etc.; in the separation and purification process, commonly used techniques include precipitation, extraction, electrolysis and adsorption. Chinese patent CN117446769A discloses a method for recycling waste lithium manganese iron phosphate batteries. Through the coupling of acid leaching, pH adjustment for impurity removal, extraction and other technologies, the full component recovery of the positive electrode material of waste lithium manganese iron phosphate batteries is achieved. However, wet recovery technology requires the use of a large amount of strong acids, strong bases, and strong oxidants, and there are problems such as large acid and alkali consumption, large wastewater discharge, and large environmental impact. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a green recycling method for positive electrode materials of waste batteries, which can realize acid-free and alkali-free, green and efficient recycling of valuable metals in waste batteries.

[0006] One object of the present invention is achieved by the following technical solutions:

[0007] A green recycling method for waste battery positive electrode materials comprises the following steps:

[0008] S1. Discharging, crushing, pyrolyzing and finely separating the waste batteries to obtain positive electrode active materials;

[0009] S2, mixing the positive electrode active material with the alkali metal compound solution, adding the mixture into a high-pressure reactor for reaction, and obtaining a solid and a lithium-containing filtrate after solid-liquid separation;

[0010] S3, adjusting the pH of the lithium-containing filtrate and performing solid-liquid separation to obtain a filter residue and a filtrate;

[0011] S4, the filtrate is purified by ion exchange resin to obtain a purified solution;

[0012] S5, the purified liquid reacts with an alkali metal carbonate to precipitate lithium, and after solid-liquid separation, lithium carbonate solid and lithium precipitation mother liquor are obtained;

[0013] S6. Solid lithium carbonate is added to water to form a slurry, carbon dioxide is introduced to carry out a carbonization reaction, and the filtrate obtained by solid-liquid separation is heated to precipitate solids to obtain battery-grade lithium carbonate.

[0014] Preferably, the waste battery is a waste lithium battery; further, the waste lithium battery is a compound of one or more of waste ternary lithium batteries, waste lithium iron phosphate batteries, waste lithium cobalt oxide batteries, waste lithium manganese oxide batteries, and waste lithium titanate batteries. Generally speaking, the positive electrode active material of the ternary lithium battery is a ternary compound of nickel, cobalt and manganese (Ni-Mn-Co), the positive electrode active material of the lithium iron phosphate battery is lithium iron phosphate (LiFePO4), the positive electrode active material of the lithium cobalt oxide battery is lithium cobalt oxide (LiCoO2), the positive electrode active material of the lithium manganate battery is lithium manganate (LiMn2O4), and the positive electrode active material of the lithium titanate battery is lithium titanate (Li4Ti5O 12 ).

[0015] Before crushing the used batteries, discharge them first to avoid potential risks during the processing.

[0016] Fine separation includes secondary crushing, screening, air separation, gravity separation and other steps. Through fine separation, positive electrode active materials, negative electrode active materials, negative electrode current collector particles, positive electrode current collector particles, battery shells and the like can be obtained.

[0017] After the battery is discharged, it is crushed and the crushed material is pyrolyzed at 450-550°C to remove organic matter such as binders. Then it is crushed for the second time. The crushed material is air-selected to remove the diaphragm and then screened at multiple stages to separate the positive and negative electrode mixed powders and copper and aluminum particles. Gravity separation is used to obtain copper particles and aluminum particles.

[0018] Preferably, in step S2, the molar ratio of the lithium element in the positive electrode active material to the alkali metal element in the alkali metal compound solution is 1:1-3.

[0019] Preferably, the concentration of the alkali metal compound solution in step S2 is 0.1 to 10 mol / L, more preferably 1 to 5 mol / L.

[0020] Preferably, the alkali metal compound in step S2 is one or more of sodium sulfate, sodium bisulfate, potassium sulfate, potassium bisulfate, sodium chloride, potassium chloride, sodium nitrate and potassium nitrate.

[0021] More preferably, the alkali metal compound is sodium sulfate and / or sodium bisulfate. Using sodium sulfate and / or sodium bisulfate to react with the positive electrode active material has a higher lithium leaching rate.

[0022] Preferably, the reaction pressure of step S2 is 0.5-10 MPa, more preferably 1-5 MPa, for example, it can be 1, 2, 3, 4 or 5 MPa; the reaction temperature is 80-250°C, more preferably 100-220°C, for example, it can be 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210 or 220°C; the reaction time is 0.5-10h, more preferably 1-5h, for example, it can be 1, 2, 3, 4 or 5h.

[0023] Preferably, in step S3, the pH of the lithium-containing filtrate is adjusted twice, the first time the pH is adjusted to 5-8, more preferably 6-7; the second time the pH is adjusted to 10-14, more preferably 11-12.

[0024] Preferably, in step S3, after the pH of the lithium-containing filtrate is adjusted for the first time, the solid-liquid separation is carried out after the reaction for 30 to 90 minutes, and the pH of the obtained filtrate is adjusted for the second time, and the solid-liquid separation is carried out after the reaction for 30 to 90 minutes.

[0025] The metal impurities in the lithium-containing filtrate are removed by adjusting the pH twice.

[0026] Step S4 specifically includes: loading the ion exchange resin into the ion exchange column, slowly passing the filtrate to be treated through the ion exchange column, controlling the flow rate of the filtrate to be 1 to 5 times the resin volume / hour, and collecting the effluent as the purified solution. The ion exchange resin can be listed as a cation exchange resin that can remove calcium and magnesium ions.

[0027] Preferably, in step S5, the molar ratio of the lithium element in the purified solution to the alkali metal in the alkali metal carbonate is 1:1-2.

[0028] Preferably, in step S5, the alkali metal carbonate includes one or more of sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate, and more preferably sodium carbonate and / or potassium carbonate.

[0029] Preferably, the lithium precipitation reaction time in step S5 is 10 to 120 minutes and the temperature is 50 to 100°C.

[0030] The lithium precipitation mother solution obtained in step S5 mainly contains the alkali metal compound in step S2. Therefore, the lithium precipitation mother solution can be returned to step S2 to replace the alkali metal compound solution and react with the positive electrode active material, thereby realizing the recycling of materials.

[0031] In step S6, lithium carbonate solid is added to water to form a slurry, preferably, the mass ratio of lithium carbonate solid to water is 1:1-20. Preferably, the purity of the introduced carbon dioxide is ≥99.9%. Preferably, the temperature of the carbonization reaction is 20-50°C, and the time is 1-5h. Preferably, the heating temperature is 80-100°C, and the heating time is 30-300min.

[0032] Preferably, the purity of battery-grade lithium carbonate is ≥99.5%.

[0033] The solid-liquid separation methods in this article include centrifugation, filtration, sedimentation, etc.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. The present invention uses sodium salt or potassium salt to recycle the positive electrode active materials of waste lithium batteries under high pressure and high temperature conditions. Since the atomic radius of sodium or potassium is relatively close to that of lithium, it is unexpectedly found that sodium or potassium atoms can be exchanged with lithium atoms in situ under the action of high pressure and high temperature, and lithium atoms can be selectively removed from the crystal structure of the positive electrode materials of waste lithium batteries, thereby achieving the purpose of preferential lithium extraction.

[0036] 2. The present invention adopts salt solution high-pressure reaction technology to realize the extraction of lithium elements in the positive electrode active materials of waste lithium-ion batteries. The entire recovery process does not use strong acid chemical reagents, avoids the use of highly corrosive chemical reagents, and is environmentally friendly. It also does not use high temperature for roasting, reduces energy consumption, and shortens the process flow. At the same time, the lithium precipitation mother liquor obtained in the process can be recycled, realizing the recycling of materials, reducing costs, reducing wastewater emissions, and further reducing the impact on the environment, which is more green and environmentally friendly.

[0037] 3. The salt solution high-pressure reaction technology adopted in the present invention can achieve a lithium leaching rate of 99%, showing a very high lithium recovery efficiency.

[0038] 4. The present invention further effectively separates the heterometallic ions in the lithium-containing filtrate by adjusting the pH value twice, and simultaneously purifies the filtrate using a cation exchange resin to further remove impurities and improve the purity of lithium carbonate.

[0039] 5. The acid-free and alkali-free recovery method of the positive electrode active material of waste lithium batteries of the present invention eliminates the high-temperature roasting and complicated chemical treatment steps, simplifies the process flow, and is easy for industrial application. DETAILED DESCRIPTION

[0040] The technical scheme of the present invention is further described below by specific embodiments. It should be understood that the specific embodiments described herein are only used to help understand the present invention and are not intended to be used for specific limitations of the present invention. Unless otherwise specified, the raw materials used in the embodiments of the present invention are all commonly used raw materials in the art, and the methods used in the embodiments are all conventional methods in the art.

[0041] Example 1

[0042] The green recycling method of waste battery positive electrode materials provided in this embodiment comprises the following steps:

[0043] (1) Waste ternary lithium-ion batteries (positive electrode active material is LiMn 0.15 Co 0.25 Ni 0.6 O) discharging, crushing, pyrolysis and fine separation to obtain positive electrode active material powder, negative electrode graphite powder, copper particles, aluminum particles and metal shell, wherein the positive electrode active material powder is subjected to subsequent steps to extract lithium, and other materials can be directly sold;

[0044] (2) The positive electrode active material powder obtained in step (1) is mixed with a 1.5 mol / L sodium sulfate solution in a molar ratio of lithium element in the positive electrode active material to sodium element in the sodium sulfate solution of 1:1.5, and the mixture is added into a high-pressure reactor to react at 160° C. and 2.0 MPa. After reacting for 2.0 h, the slurry is subjected to solid-liquid separation to obtain a solid and a lithium-containing filtrate.

[0045] (3) adding 1 mol / L NaOH to the lithium-containing filtrate obtained in step (1) to adjust the pH to 6.0, and then reacting for 20 minutes to separate the solid and liquid to obtain a filter residue and a filtrate #1;

[0046] (4) adding 1 mol / L NaOH to the filtrate #1 obtained in step (3) to adjust the pH to 12.0, and then reacting for 20 minutes to separate the solid and the liquid to obtain a filter residue and a filtrate #2;

[0047] (5) purifying the filtrate #2 obtained in step (4) by passing it through a cation exchange resin at a flow rate of 3 times the resin volume / hour to obtain a purified solution;

[0048] (6) The purified solution is then reacted with a 2 mol / L sodium carbonate solution to react lithium. The molar ratio of lithium element in the purified solution to sodium metal in the sodium carbonate is 1:1.1. The lithium precipitation reaction is carried out at 60° C. for 60 min. After solid-liquid separation, lithium carbonate solid and lithium precipitation mother liquor can be obtained. The main component of the lithium precipitation mother liquor is sodium sulfate. Therefore, the lithium precipitation mother liquor can be returned to step (2) to replace the sodium sulfate solution and react with the positive electrode active material powder.

[0049] (7) Then the lithium carbonate obtained in step (6) is added to water for slurry preparation (the mass ratio of lithium carbonate to water is 1:8), 99.99% carbon dioxide is introduced for carbonization reaction (30° C., 2 h), and finally heated (90° C., 3 h) for precipitation, thereby obtaining battery-grade lithium carbonate with a purity of 99.7%.

[0050] In this embodiment, in the sodium sulfate solution high pressure reaction lithium extraction technology in step (2), the lithium leaching rate is about 98.5%.

[0051] Lithium leaching rate = 100%*C*V / m,

[0052] Wherein, C is the concentration of lithium in the lithium-containing filtrate of step (2) in g / L, V is the total volume L of the lithium-containing filtrate, and m is the mass g of lithium in the positive electrode active material powder.

[0053] Example 2

[0054] The green recycling method of waste battery positive electrode materials provided in this embodiment comprises the following steps:

[0055] (1) Discharging, crushing, pyrolyzing and finely separating waste lithium iron phosphate batteries (positive electrode active material is LiFePO4) to obtain positive electrode active material powder, negative electrode graphite powder, copper particles, aluminum particles and metal shells, wherein the positive electrode active material powder is subjected to subsequent steps to extract lithium, and other materials can be directly sold;

[0056] (2) The positive electrode active material powder obtained in step (1) is mixed with a 2 mol / L potassium sulfate solution in a molar ratio of lithium element in the positive electrode active material to potassium element in the potassium sulfate solution of 1:1.8, and the mixture is added into a high-pressure reactor to react at 180° C. and 2.4 MPa. After reacting for 2.5 hours, the slurry is subjected to solid-liquid separation to obtain a solid and a lithium-containing filtrate.

[0057] (3) adding 1 mol / L NaOH to the lithium-containing filtrate obtained in step (1) to adjust the pH to 7.0, and then reacting for 15 minutes to separate the solid and liquid to obtain a filter residue and a filtrate #1;

[0058] (4) adding 1 mol / L NaOH to the filtrate #1 obtained in step (3) to adjust the pH to 11.0, and then reacting for 15 minutes to separate the solid and the liquid to obtain a filter residue and a filtrate #2;

[0059] (5) purifying the filtrate #2 obtained in step (4) by passing it through a cation exchange resin at a flow rate of 4 times the resin volume / hour to obtain a purified solution;

[0060] (6) The purified liquid is then reacted with a 1.5 mol / L potassium carbonate solution to react lithium. The molar ratio of the lithium element in the purified liquid to the potassium metal in the potassium carbonate is 1:1.2. The lithium precipitation reaction is carried out at 70° C. for 50 min. After solid-liquid separation, lithium carbonate solid and lithium precipitation mother liquor can be obtained. The main component of the lithium precipitation mother liquor is potassium sulfate. Therefore, the lithium precipitation mother liquor can be returned to step (2) to replace the potassium sulfate solution and react with the positive electrode active material powder;

[0061] (7) Then the lithium carbonate obtained in step (6) is added to water for slurry preparation (the mass ratio of lithium carbonate to water is 1:10), 99.99% carbon dioxide is introduced for carbonization reaction (30° C., 3 h), and finally heated (95° C., 3 h) for precipitation, thereby obtaining battery-grade lithium carbonate with a purity of 99.6%.

[0062] In this embodiment, in the potassium sulfate solution high pressure reaction lithium extraction technology in step (2), the lithium leaching rate is about 92.2%.

[0063] Example 3

[0064] The green recycling method of waste battery positive electrode materials provided in this embodiment comprises the following steps:

[0065] (1) Waste ternary lithium-ion batteries (positive electrode active material is LiMn 0.15 Co 0.25 Ni 0.6 O) discharging, crushing, pyrolysis and fine separation to obtain positive electrode active material powder, negative electrode graphite powder, copper particles, aluminum particles and metal shell, wherein the positive electrode active material powder is subjected to subsequent steps to extract lithium, and other materials can be directly sold;

[0066] (2) The positive electrode active material powder obtained in step (1) is mixed with 1 mol / L potassium sulfate solution in a molar ratio of lithium element in the positive electrode active material to potassium element in the potassium sulfate solution of 1:1.4, and the mixture is added into a high-pressure reactor to react at 80° C. and 0.5 MPa. After reacting for 6.0 h, the slurry is subjected to solid-liquid separation to obtain a solid and a lithium-containing filtrate.

[0067] (3) adding 1 mol / L NaOH to the lithium-containing filtrate obtained in step (1) to adjust the pH to 8.0, and then reacting for 25 minutes to separate the solid and liquid to obtain a filter residue and a filtrate #1;

[0068] (4) adding 1 mol / L NaOH to the filtrate #1 obtained in step (3) to adjust the pH to 14.0, and then reacting for 25 minutes to separate the solid and the liquid to obtain a filter residue and a filtrate #2;

[0069] (5) purifying the filtrate #2 obtained in step (4) by passing it through a cation exchange resin at a flow rate of 5 times the resin volume / hour to obtain a purified solution;

[0070] (6) The purified liquid is then reacted with a 2.5 mol / L potassium carbonate solution to react lithium. The molar ratio of lithium element in the purified liquid to potassium metal in potassium carbonate is 1:1.3. The lithium precipitation reaction is carried out at 80°C for 80 minutes. After solid-liquid separation, lithium carbonate solid and lithium precipitation mother liquor can be obtained. The main component of the lithium precipitation mother liquor is potassium sulfate. Therefore, the lithium precipitation mother liquor can be returned to step (2) to replace the potassium sulfate solution and react with the positive electrode active material powder;

[0071] (7) Then the lithium carbonate obtained in step (6) is added to water for slurry preparation (the mass ratio of lithium carbonate to water is 1:9), 99.99% carbon dioxide is introduced for carbonization reaction (30° C., 1.5 h), and finally heated (85° C., 3 h) for precipitation, thereby obtaining battery-grade lithium carbonate with a purity of 99.8%.

[0072] In this embodiment, in the potassium sulfate solution high pressure reaction lithium extraction technology in step (2), the lithium leaching rate is about 78.5%.

[0073] Example 4

[0074] The green recycling method of waste battery positive electrode materials provided in this embodiment comprises the following steps:

[0075] (1) Waste ternary lithium-ion batteries (positive electrode active material is LiMn 0.15 Co 0.25 Ni 0.6 O) discharging, crushing, pyrolysis and fine separation to obtain positive electrode active material powder, negative electrode graphite powder, copper particles, aluminum particles and metal shell, wherein the positive electrode active material powder is subjected to subsequent steps to extract lithium, and other materials can be directly sold;

[0076] (2) The positive electrode active material powder obtained in step (1) is mixed with a 3 mol / L potassium hydrogen sulfate solution in a molar ratio of lithium element in the positive electrode active material to potassium element in the potassium hydrogen sulfate solution of 1:1.6, and the mixture is added to a high-pressure reactor to react at 250° C. and 4 MPa. After reacting for 0.5 h, the slurry is subjected to solid-liquid separation to obtain a solid and a lithium-containing filtrate.

[0077] (3) adding 2 mol / L NaOH to the lithium-containing filtrate obtained in step (1) to adjust the pH to 5.5, and then reacting for 15 min and separating the solid and the liquid to obtain a filter residue and a filtrate #1;

[0078] (4) adding 2 mol / L NaOH to the filtrate #1 obtained in step (3) to adjust the pH to 10, and then reacting for 15 minutes to separate the solid and the liquid to obtain a filter residue and a filtrate #2;

[0079] (5) purifying the filtrate #2 obtained in step (4) by passing it through a cation exchange resin at a flow rate of 2 times the resin volume / hour to obtain a purified solution;

[0080] (6) The purified solution is then reacted with a 2.5 mol / L potassium carbonate solution to precipitate lithium. The molar ratio of lithium element in the purified solution to potassium metal in potassium carbonate is 1:1.3. The lithium precipitation reaction is carried out at 90° C. for 80 min. After solid-liquid separation, lithium carbonate solid and lithium precipitation mother liquor can be obtained. The main component of the lithium precipitation mother liquor is potassium sulfate.

[0081] (7) Then the lithium carbonate obtained in step (6) is added to water for slurry preparation (the mass ratio of lithium carbonate to water is 1:11), 99.99% carbon dioxide is introduced for carbonization reaction (30° C., 3 h), and finally heated (92° C., 4 h) for precipitation, thereby obtaining battery-grade lithium carbonate with a purity of 99.9%.

[0082] In this embodiment, in the potassium bisulfate solution high pressure reaction lithium extraction technology in step (2), the lithium leaching rate is about 85.7%.

[0083] Example 5

[0084] The green recycling method of waste battery positive electrode materials provided in this embodiment comprises the following steps:

[0085] (1) Waste ternary lithium-ion batteries (positive electrode active material is LiMn 0.15 Co 0.25 Ni 0.6 O) discharging, crushing, pyrolysis and fine separation to obtain positive electrode active material powder, negative electrode graphite powder, copper particles, aluminum particles and metal shell, wherein the positive electrode active material powder is subjected to subsequent steps to extract lithium, and other materials can be directly sold;

[0086] (2) The positive electrode active material powder obtained in step (1) is mixed with a 4 mol / L sodium bisulfate solution in a molar ratio of lithium element in the positive electrode active material to sodium element in the sodium bisulfate solution of 1:1.8, and the mixture is added to a high-pressure reactor to react at 220° C. and 3 MPa. After reacting for 5 hours, the slurry is subjected to solid-liquid separation to obtain a solid and a lithium-containing filtrate.

[0087] (3) adding 2 mol / L NaOH to the lithium-containing filtrate obtained in step (1) to adjust the pH to 7.5, and then reacting for 15 min to separate the solid and liquid to obtain a filter residue and a filtrate #1;

[0088] (4) adding 2 mol / L NaOH to the filtrate #1 obtained in step (3) to adjust the pH to 12.5, and then reacting for 15 minutes to separate the solid and the liquid to obtain a filter residue and a filtrate #2;

[0089] (5) purifying the filtrate #2 obtained in step (4) by passing it through a cation exchange resin at a flow rate of 23 times the resin volume / hour to obtain a purified solution;

[0090] (6) The purified solution is then reacted with a 3 mol / L sodium carbonate solution to precipitate lithium. The molar ratio of lithium element in the purified solution to sodium metal in the sodium carbonate is 1:1.5. The lithium precipitation reaction is carried out at 90° C. for 90 min. After solid-liquid separation, lithium carbonate solid and lithium precipitation mother liquor can be obtained. The main component of the lithium precipitation mother liquor is sodium sulfate.

[0091] (7) Then, the lithium carbonate obtained in step (6) is added to water for slurry preparation (the mass ratio of lithium carbonate to water is 1:12), 99.99% carbon dioxide is introduced for carbonization reaction (30° C., 2.5 h), and finally heated (92° C., 3.5 h) for precipitation, thereby obtaining battery-grade lithium carbonate with a purity of 99.8%.

[0092] In this embodiment, in the sodium bisulfate solution high pressure reaction lithium extraction technology in step (2), the lithium leaching rate is about 95.8%.

[0093] Example 6

[0094] The green recycling method of waste battery positive electrode materials in Example 6 is different from that in Example 1 in that step (2) of Example 6 is: mixing the positive electrode active material powder obtained in step (1) with 1.5 mol / L sodium bisulfate solution in a molar ratio of lithium element in the positive electrode active material to sodium element in the sodium bisulfate solution of 1:1.5, adding the mixture to a high-pressure reactor, reacting at 160°C and 2.0 MPa, reacting for 2.0 hours, and performing solid-liquid separation on the slurry to obtain a solid and a lithium-containing filtrate. The other steps are the same as those in Example 1.

[0095] In this embodiment, in the sodium bisulfate solution high pressure reaction lithium extraction technology in step (2), the lithium leaching rate is about 94.3%.

[0096] Example 7

[0097] The green recycling method of waste battery positive electrode materials in Example 7 is different from that in Example 1 in that step (2) of Example 7 is: mixing the positive electrode active material powder obtained in step (1) with 1.5 mol / L potassium sulfate solution in a molar ratio of lithium element in the positive electrode active material to potassium element in the potassium sulfate solution of 1:1.5, adding the mixture to a high-pressure reactor, reacting at 160°C and 2.0 MPa, reacting for 2.0 h, and performing solid-liquid separation on the slurry to obtain a solid and a lithium-containing filtrate. The other steps are the same as those in Example 1.

[0098] In this embodiment, in the potassium sulfate solution high pressure reaction lithium extraction technology in step (2), the lithium leaching rate is about 91.4%.

[0099] Example 8

[0100] The green recycling method of waste battery positive electrode materials in Example 8 is different from that in Example 1 in that step (2) of Example 8 is: mixing the positive electrode active material powder obtained in step (1) with 1.5 mol / L potassium hydrogen sulfate solution in a molar ratio of lithium element in the positive electrode active material to potassium element in the potassium hydrogen sulfate solution of 1:1.5, adding the mixture to a high-pressure reactor, reacting at 160°C and 2.0 MPa, reacting for 2.0 hours, and performing solid-liquid separation on the slurry to obtain a solid and a lithium-containing filtrate. The other steps are the same as those in Example 1.

[0101] In this embodiment, in the potassium bisulfate solution high pressure reaction lithium extraction technology in step (2), the lithium leaching rate is about 83.6%.

[0102] Example 9

[0103] The green recycling method of waste battery positive electrode materials in Example 9 is different from that in Example 1 in that step (2) of Example 9 is: mixing the positive electrode active material powder obtained in step (1) with 1.5 mol / L sodium chloride solution in a molar ratio of lithium element in the positive electrode active material to sodium element in the sodium chloride solution of 1:1.5, adding the mixture to a high-pressure reactor, reacting at 160°C and 2.0 MPa, reacting for 2.0 h, and performing solid-liquid separation on the slurry to obtain a solid and a lithium-containing filtrate. The other steps are the same as those in Example 1.

[0104] In this embodiment, in the sodium chloride solution high pressure reaction lithium extraction technology in step (2), the lithium leaching rate is about 80.7%.

[0105] Example 10

[0106] The green recycling method of waste battery positive electrode materials in Example 10 is different from that in Example 1 in that step (2) of Example 10 is: mixing the positive electrode active material powder obtained in step (1) with 1.5 mol / L sodium nitrate solution in a molar ratio of lithium element in the positive electrode active material to sodium element in the sodium nitrate solution of 1:1.5, adding the mixture to a high-pressure reactor, reacting at 160° C. and 2.0 MPa, and after reacting for 2.0 h, performing solid-liquid separation on the slurry to obtain a solid and a lithium-containing filtrate. The other steps are the same as those in Example 1.

[0107] In this embodiment, in the sodium nitrate solution high pressure reaction lithium extraction technology in step (2), the lithium leaching rate is about 81.5%.

[0108] Comparative Example 1

[0109] The difference between Comparative Example 1 and Example 1 is that step (2) of Comparative Example 1 is specifically as follows: the positive electrode active material powder obtained in step (1) is mixed with 1.5 mol / L sodium sulfate solution according to a molar ratio of lithium element in the positive electrode active material to sodium element in the sodium sulfate solution of 1:1.5, added into a high-pressure reactor, reacted at 40°C and 2.0 MPa, and after reacting for 2.0 h, the slurry is subjected to solid-liquid separation to obtain a solid and a lithium-containing filtrate.

[0110] The other steps are the same as in Example 1.

[0111] In this embodiment, in the sodium sulfate solution high pressure reaction lithium extraction technology in step (2), the lithium leaching rate is about 20.8%.

[0112] Comparative Example 2

[0113] The difference between Comparative Example 2 and Example 1 is that step (2) of Comparative Example 2 is specifically as follows: the positive electrode active material powder obtained in step (1) is mixed with 1.5 mol / L sodium sulfate solution according to a molar ratio of lithium element in the positive electrode active material to sodium element in the sodium sulfate solution of 1:1.5, added into a high-pressure reactor, reacted at 160°C under normal pressure, and after reacting for 2.0 hours, the slurry is subjected to solid-liquid separation to obtain a solid and a lithium-containing filtrate.

[0114] The other steps are the same as in Example 1.

[0115] In this embodiment, in the sodium sulfate solution high pressure reaction lithium extraction technology in step (2), the lithium leaching rate is about 35.9%.

[0116] The various aspects, embodiments, and features of the present invention should be considered to be illustrative in all aspects and not limiting of the present invention, the scope of which is defined solely by the claims. Other embodiments, modifications, and uses will be apparent to those skilled in the art without departing from the spirit and scope of the claimed invention.

[0117] In the preparation method of the present invention, the order of each step is not limited to the order listed. For those skilled in the art, without creative work, the order of each step is also within the protection scope of the present invention. In addition, two or more steps or actions can be performed simultaneously.

[0118] Finally, it should be noted that the specific embodiments described herein are merely examples of the present invention, and are not intended to limit the implementation methods of the present invention. A person skilled in the art of the present invention may make various modifications or supplements to the specific embodiments described, or replace them in a similar manner. It is not necessary and impossible to provide all examples of all implementation methods here. However, these obvious changes or modifications derived from the essential spirit of the present invention still fall within the scope of protection of the present invention, and interpreting them as any additional limitation is contrary to the spirit of the present invention.

Claims

1. A green recycling method for waste battery positive electrode materials, characterized in that: The following steps are involved: S1. Discharging, crushing, pyrolyzing and finely separating the waste batteries to obtain positive electrode active materials; S2, mixing the positive electrode active material with the alkali metal compound solution, adding the mixture into a high-pressure reactor for reaction, and obtaining a solid and a lithium-containing filtrate after solid-liquid separation; S3, adjusting the pH of the lithium-containing filtrate and performing solid-liquid separation to obtain a filter residue and a filtrate; S4, the filtrate is purified by ion exchange resin to obtain a purified solution; S5, the purified liquid reacts with an alkali metal carbonate to precipitate lithium, and after solid-liquid separation, lithium carbonate solid and lithium precipitation mother liquor are obtained; S6. Solid lithium carbonate is added to water to form a slurry, carbon dioxide is introduced to carry out a carbonization reaction, and the filtrate obtained by solid-liquid separation is heated to precipitate solids to obtain battery-grade lithium carbonate.

2. The green recycling method of waste battery positive electrode materials according to claim 1, characterized in that: The waste batteries are waste lithium batteries; The waste lithium battery is a compound of one or more of waste ternary lithium batteries, waste lithium iron phosphate batteries, waste lithium cobalt oxide batteries, waste lithium manganese oxide batteries, and waste lithium titanate batteries.

3. The green recycling method of waste battery positive electrode materials according to claim 1, characterized in that: In step S2, the molar ratio of lithium element in the positive electrode active material to alkali metal element in the alkali metal compound solution is 1:1-3; And / or, the concentration of the alkali metal compound solution in step S2 is 0.1 to 10 mol / L.

4. The green recycling method of waste battery positive electrode materials according to claim 1, characterized in that: The alkali metal compound in step S2 is one or more of sodium sulfate, sodium bisulfate, potassium sulfate, potassium bisulfate, sodium chloride, potassium chloride, sodium nitrate, and potassium nitrate.

5. A green recycling method for waste battery positive electrode materials according to claim 1 or 4, characterized in that: The reaction pressure of step S2 is 0.5-10 MPa, the reaction temperature is 80-250° C., and the reaction time is 0.5-10 h.

6. The green recycling method of waste battery positive electrode materials according to claim 1, characterized in that: In step S3, the pH of the lithium-containing filtrate is adjusted twice, the first time the pH is adjusted to 5-8, and the second time the pH is adjusted to 10-14; After the pH of the lithium-containing filtrate is adjusted for the first time, the solid-liquid separation is carried out after the reaction for 30 to 90 minutes, and the pH of the obtained filtrate is adjusted for the second time, and the solid-liquid separation is carried out after the reaction for 30 to 90 minutes.

7. A green recycling method for waste battery positive electrode materials according to claim 1 or 3, characterized in that: In step S5, the molar ratio of the lithium element in the purified solution to the alkali metal in the alkali metal carbonate is 1:1-2.

8. The green recycling method of waste battery positive electrode materials according to claim 1, characterized in that: The alkali metal carbonate includes one or more of sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate.

9. The green recycling method of waste battery positive electrode materials according to claim 1, characterized in that: The lithium precipitation reaction time in step S5 is 10 to 120 minutes, and the temperature is 50 to 100°C.

10. The green recycling method of waste battery positive electrode materials according to claim 1, characterized in that: In step S6, the mass ratio of lithium carbonate solid to water is 1:1 to 20; The purity of the introduced carbon dioxide is ≥99.9%; The temperature of the carbonization reaction is 20-50°C and the time is 1-5h; The heating temperature is 80-100°C, and the heating time is 30-300 minutes.