Method for recycling battery powder in whole chain integration

Abstract

The application discloses a method for recycling battery powder in an integrated whole chain, which comprises the following steps: firstly, the content of copper and aluminum in the subsequent separation process is reduced as much as possible by using the method of centrifugal gravity separation, so as to reduce the cost of impurity removal; and secondly, the battery powder is subjected to aerobic roasting, so that the battery powder reacts with iron sulfate, H2O2 and sulfuric acid. On the one hand, the long-chain organic matters such as the binder and the carbon-coated film attached to the surface of the lithium iron phosphate positive active material are removed, so that the hydrophilicity of the positive active material is restored, and the separation effect between the positive and negative active materials is enhanced. On the other hand, the aerobic roasting can make the battery powder react with iron sulfate, H2O2 and sulfuric acid to generate roasting products such as lithium sulfate. The lithium in the products after the aerobic roasting can be extracted by using water, and no reagent other than water is needed in the lithium extraction step, so that the lithium extraction efficiency is further improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery recycling, in particular to a method for recycling battery powder in a full-chain integrated manner. BACKGROUND

[0002] In recent years, with the rapid development of the new energy industry, the advantages of lithium ion batteries such as high energy density, high voltage, good cycle performance, long service life, small self-discharge and environmental friendliness have become one of the important driving forces for the development of new energy, and are widely used in important fields such as electric vehicles, energy storage systems and smart grids. At present, lithium ion batteries can be divided into ternary lithium batteries, lithium iron phosphate batteries, lithium cobalt batteries and lithium manganese batteries according to the positive electrode material. Among them, the use proportion of lithium iron phosphate batteries in the market is increasing because of their excellent cycle performance and safety performance. In the future, lithium iron phosphate batteries may become the main power supply device for new energy vehicles.

[0003] With the increasing market share of lithium iron phosphate batteries, the total amount of scrap lithium iron phosphate batteries in the market is also increasing. Since there are harmful chemicals such as electrolyte in the battery, from the aspects of environment and resource utilization, it is necessary to recycle and process them. For the recycling of lithium iron phosphate batteries, researchers mainly focus on the repair and regeneration of the positive electrode material of lithium iron phosphate batteries and the recovery of Li, Fe and P elements in lithium iron phosphate. There are few reports on the recovery of negative graphite material in lithium iron phosphate battery powder. The unrecovered graphite is regarded as hazardous waste and needs to be outsourced for processing, which indirectly increases the production cost of enterprises.

[0004] In view of this, the present application is proposed. SUMMARY

[0005] The purpose of the present application is to provide a method for recycling battery powder in a full-chain integrated manner, which recovers graphite and lithium in the battery powder.

[0006] The present application is implemented as follows:

[0007] In a first aspect, the present application provides a method for recycling battery powder in a full-chain integrated manner, comprising:

[0008] Oxygen roasting, oxygen roasting is performed on a mixture of battery powder, iron sulfate, H2O2 and sulfuric acid to obtain a roasting material, wherein the battery powder is obtained by removing copper, aluminum and separators after discharging and crushing of lithium iron phosphate batteries;

[0009] Water leaching of lithium, mixing the roasting material with water to leach lithium and perform solid-liquid separation to obtain a lithium-containing filtrate and a battery powder after lithium leaching;

[0010] Flotation, using a flotation machine to float the battery powder after lithium leaching to obtain flotation froth containing graphite and flotation tailings containing phosphorus-iron material.

[0011] In an optional embodiment, the temperature of the aerobic roasting step is 300-500°C and the time is 0.5-2h.

[0012] In an optional embodiment, the molar ratio of sulfate ion to lithium ion in the mixture is (0.5-1.5):1.

[0013] In an optional embodiment, the molar ratio of sulfuric acid to ferric sulfate in the mixture is 1:1.

[0014] In an optional embodiment, the mass ratio of H2O2 to battery powder in the mixture is (0.1-0.2):1.

[0015] In an optional embodiment, in the water leaching lithium step, the liquid-to-solid ratio in the pre-leaching liquid is (3-7):1ml / g and the leaching time is 50-70min.

[0016] In an optional embodiment, the preparation of the battery powder comprises:

[0017] Pretreatment, discharging and crushing the lithium iron phosphate battery to obtain crushed material, then screening the crushed material using a 10-40 mesh screen to obtain a first undersize material containing battery powder and fine copper-aluminum particles and a first oversize material containing copper-aluminum and plastic separator;

[0018] First centrifugal gravity separation of the first undersize material using a concentrator, the tailings outlet obtaining a mixture of battery powder and aluminum and the concentrate outlet obtaining copper-containing material; in the first centrifugal gravity separation step, the backflush water flow rate of the concentrator is 20-30m / s and the barrel rotation speed is 300-700rpm;

[0019] Second centrifugal gravity separation of the mixture of battery powder and aluminum using a concentrator, the tailings outlet obtaining battery powder-containing material and the concentrate outlet obtaining aluminum-containing material; in the second centrifugal gravity separation step, the backflush water flow rate of the concentrator is 12-18m / s and the barrel rotation speed is 400-800rpm;

[0020] Separating the solids in the battery powder-containing material and drying to obtain the battery powder;

[0021] Preferably, mixing the first oversize material with N-methyl pyrrolidone and water under ultrasonic conditions to obtain a mixed liquid, screening the mixed liquid using an 80-120 mesh screen to obtain a second undersize material containing battery powder and a second oversize material containing copper-aluminum and separator;

[0022] Feeding the second oversize material into a shaking table, the concentrate outlet obtaining copper-containing material and the tailings outlet obtaining a mixture of aluminum and separator;

[0023] The mixture containing aluminum and diaphragm is dried and air separated to obtain aluminum-containing material and diaphragm-containing material;

[0024] More preferably, the N-methyl pyrrolidone is used in an amount of 1wt%-5wt% of the mixed solution.

[0025] In an optional embodiment, the flotation step comprises one roughing, four cleaning and two scavenging, and the roughing, cleaning and scavenging steps all add adjusting agent, frother and collector;

[0026] Preferably, the adjusting agent is at least one selected from sodium carboxymethyl cellulose, sodium humate and sulfuric acid, and is used in an amount of 50g / t-300g / t.

[0027] Preferably, the frother is 2# oil, and is used in an amount of 20g / t-200g / t.

[0028] Preferably, the collector is kerosene, and is used in an amount of 20g / t-500g / t.

[0029] In an optional embodiment, the graphite in the flotation froth is separated and graphitized to obtain a battery-grade graphite product, and the graphitization treatment comprises mixing the separated graphite with an additive in a mass ratio of 2-5 and then heat treating at 800-1200℃.

[0030] Preferably, the additive is at least one selected from pitch, phenolic resin and glucose.

[0031] In an optional embodiment, the flotation tailings containing phosphorus iron material are mixed with sulfuric acid, the pH value is adjusted to 0.5-2, and then solid-liquid separation is performed, followed by adding H2O2 to adjust the pH value to 3.5-7, and then solid-liquid separation is performed to obtain a ferric phosphate solution.

[0032] Preferably, the mass ratio of H2O2 to flotation tailings is 0.08-0.15.

[0033] The present application has the following beneficial effects:

[0034] In the embodiments of the present application, firstly, the method of centrifugal gravity separation is used to reduce the content of copper and aluminum in the subsequent sorting process as much as possible, thereby reducing the cost of impurity removal. Secondly, the battery powder is subjected to aerobic roasting. The aerobic roasting can cause the battery powder to react with ferric sulfate, H2O2 and sulfuric acid. On the one hand, under the dual action of air and H2O2, the long-chain organic matters such as the binder and carbon-coated film attached to the surface of the lithium iron phosphate positive electrode active material can be fully removed, so that the positive electrode material restores hydrophilicity and the separation effect between the positive and negative electrode materials is enhanced. If anaerobic roasting is used, the long-chain organic matters such as the binder attached to the surface of the lithium iron phosphate positive electrode active material can be carbonized and continue to adhere to the surface of the lithium iron phosphate positive electrode active material, so that the hydrophilicity of the lithium iron phosphate positive electrode active material in water is reduced, thereby increasing the separation difficulty between the positive and negative electrode materials. On the other hand, the aerobic roasting can cause the battery powder to react with ferric sulfate, H2O2 and sulfuric acid to generate roasting products such as lithium sulfate. The products after aerobic roasting can be subjected to lithium extraction by water in the subsequent step. The lithium extraction step does not need to add reagents other than water, thereby further improving the lithium extraction efficiency. The aerobic roasting in the embodiments of the present application is beneficial to improving the separation effect of the positive and negative electrode materials and can also be helpful to water leaching of lithium. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0036] Figure 1 The flowchart of the method of full-chain integrated battery powder recycling in the embodiment 1 of the present application;

[0037] Figure 2 The flowchart of the flotation step in the embodiment 1 of the present application. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be described clearly and completely. The specific conditions not mentioned in the embodiments are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments not mentioned by the manufacturer are all conventional products that can be obtained by market purchase.

[0039] The embodiments of the present application provide a method for full-chain integrated battery powder recycling, comprising:

[0040] The mixture of the battery powder, the iron sulfate, the H2O2 and the sulfuric acid is subjected to aerobic roasting to obtain a roasted material, wherein the battery powder is obtained by discharging, crushing and removing copper, aluminum and a separator from a lithium iron phosphate battery;

[0041] The lithium is extracted by water, the roasted material is mixed with water to extract lithium and to separate the solid and the liquid, to obtain a lithium-containing filtrate and a battery powder after lithium extraction;

[0042] The battery powder after lithium extraction is subjected to flotation by using a flotation machine to obtain flotation froth containing graphite and flotation tailings containing phosphorus-iron material.

[0043] In the embodiment, the battery powder is subjected to aerobic roasting first. The aerobic roasting can make the battery powder react with the iron sulfate, the H2O2 and the sulfuric acid. On the one hand, under the dual action of air and H2O2, the long-chain organic binder attached to the surface of the lithium iron phosphate positive active material can be fully removed, so that the positive active material restores hydrophilicity and the separation effect between the positive and negative active materials is enhanced. If anaerobic roasting is used, the long-chain organic binder attached to the surface of the lithium iron phosphate positive active material can be carbonized and continue to adhere to the surface of the lithium iron phosphate positive active material, so that the hydrophilicity of the lithium iron phosphate positive active material in water is reduced, and the separation difficulty between the positive and negative active materials is increased. On the other hand, the aerobic roasting can make the battery powder react with the iron sulfate, the H2O2 and the sulfuric acid to generate lithium sulfate and other roasting products. The products after aerobic roasting can be extracted by water in the subsequent step, and no reagent other than water is needed in the lithium extraction step, which further improves the lithium extraction efficiency. The aerobic roasting in the embodiment is beneficial to improving the separation effect of the positive and negative active materials and can help the lithium extraction by water.

[0044] In the aerobic roasting step, the sulfuric acid needs to be added. The oxidizing and acidic sulfuric acid is beneficial to the oxidation of long-chain organic matter and provides sulfate to combine with lithium to generate water-soluble lithium sulfate, which is beneficial to the subsequent lithium extraction. After the H2O2 is uniformly mixed with the battery powder, oxygen can be released during the aerobic roasting process, which reduces the time for the oxygen in the external roasting atmosphere to diffuse into the mixture, so that the battery powder can be fully immersed in the oxygen atmosphere, and the aerobic roasting can be more fully and quickly performed. The iron sulfate can provide sulfate for reaction with lithium and can provide iron for reaction with phosphate during the aerobic roasting process, which is beneficial to the subsequent lithium extraction of water-soluble lithium sulfate and the separation of hydrophilic iron phosphate from graphite, thereby improving the recovery rate of lithium and graphite and the carbon content in the graphite product.

[0045] In an optional embodiment, the temperature of the aerobic roasting step is 300-500°C, specifically, it can be 300°C, 350°C, 400°C, 450°C, 500°C, or any value between 300-500°C, and the time is 0.5-2h, specifically, it can be 0.5h, 1h, 1.5h, 2h, or any value between 0.5-2h.

[0046] The temperature of the aerobic roasting step will affect the recovery rate of lithium and the recovery rate and carbon content of the subsequent recovered graphite product. If the roasting temperature is too low, on the one hand, it will lead to incomplete reaction of lithium iron phosphate material in the lithium iron phosphate battery with ferric sulfate and hydrogen peroxide, and cannot be completely converted into Li2SO4, resulting in a decrease in lithium leaching rate. On the other hand, a too low temperature will lead to a decrease in the removal effect of the binder and other substances on the lithium iron phosphate battery powder, and the lithium iron phosphate material will still show hydrophobicity, resulting in poor separation effect of the lithium iron phosphate material from the hydrophobic graphite negative electrode in the flotation process, and thus leading to a decrease in the carbon content of the recovered graphite product. If the oxidation roasting temperature is too high, O2 will react with LiFePO4 before ferric sulfate and sulfuric acid, generating Li3Fe2(PO4)3 which is relatively stable in chemical properties, and cannot be decomposed to generate Li2SO4, making it difficult to leach lithium and resulting in a decrease in lithium leaching rate.

[0047] In an optional embodiment, the molar ratio of sulfate to lithium ions in the mixture is (0.5-1.5):1, specifically, it can be 0.5:1, 0.7:1, 0.9:1, 1.1:1, 1.3:1, 1.5:1, or any value between 0.5-1.5:1. If the amount of sulfate is too small, lithium cannot be completely converted into lithium sulfate, and if the amount of sulfate is too large, the excess sulfate cannot be completely reacted, resulting in waste of raw materials.

[0048] In an optional embodiment, the molar ratio of sulfuric acid to ferric sulfate in the mixture is (0.5-1.5):1, specifically, it can be 0.5:1, 0.7:1, 0.9:1, 1.1:1, 1.3:1, 1.5:1, or any value between 0.5-1.5:1. If the amount of iron ions is too small, it will be difficult to react completely with phosphate ions, and thus the lithium leaching rate will decrease. If the amount of iron ions is too large, the excess iron ions cannot be completely reacted, resulting in waste of raw materials.

[0049] In an optional embodiment, the mass ratio of H2O2 to battery powder in the mixture is (0.1-0.2):1, and specifically can be 0.1:1, 0.12:1, 0.14:1, 0.16:1, 0.18:1, 0.2:1, or any value between 0.1 and 0.2. Excessive H2O2 consumes too much energy, and the excess oxygen released by decomposition cannot be fully reacted, resulting in waste of raw materials and increase of energy consumption. If H2O2 is insufficient, the oxygen released cannot meet the needs of the reaction, which is not conducive to the separation of graphite and positive electrode materials.

[0050] In an optional embodiment, in the water leaching lithium step, the liquid-solid ratio of the pre-leaching liquid is (3-7):1ml / g, and specifically can be 3:1ml / g, 4:1ml / g, 5:1ml / g, 6:1ml / g, 7:1ml / g, or any value between 3 and 7:1ml / g, and the leaching time is 50-70min, and specifically can be 50min, 55min, 60min, 65min, 70min, or any value between 50min and 70min.

[0051] In this embodiment, water is used to leach lithium. Increasing the liquid-solid ratio of the pre-leaching liquid or extending the leaching time can improve the leaching efficiency, but also increases the water consumption or reduces the efficiency, and increasing the liquid-solid ratio reduces the concentration of lithium ions in the leaching liquid, which is not conducive to the enrichment of lithium ions.

[0052] In an optional embodiment, the preparation of the battery powder comprises:

[0053] Pretreatment: discharging and crushing the lithium iron phosphate battery to obtain crushed material, and then screening the crushed material using a 10-40 mesh screen to obtain a first undersize material containing battery powder and fine copper-aluminum particles, and a first oversize material containing copper-aluminum and plastic separators;

[0054] First centrifugal gravity separation of the first undersize material using a concentrator, to obtain a mixture of battery powder and aluminum from the tailings outlet, and a copper-containing material from the concentrate outlet; in the first centrifugal gravity separation step, the backflush water flow rate of the concentrator is 20-30m / s, and the barrel speed is 300-700rpm;

[0055] Second centrifugal gravity separation of the mixture of battery powder and aluminum using a concentrator, to obtain a battery powder-containing material from the tailings outlet, and an aluminum-containing material from the concentrate outlet; in the second centrifugal gravity separation step, the backflush water flow rate of the concentrator is 12-18m / s, and the barrel speed is 400-800rpm;

[0056] Separating the solids in the battery powder-containing material and drying to obtain the battery powder.

[0057] The embodiment of the present application utilizes the Nelson concentrator, adopts twice centrifugal gravity separation, and sequentially separates copper and aluminum in the first screen undersize material to obtain battery powder with low copper and aluminum content. Through the centrifugal gravity separation mode, the density difference between Cu, Al and battery powder is increased, fine Cu and Al in the battery powder due to crushing are recovered, the Cu and Al content in the lithium iron phosphate battery powder is reduced, and the impurity removal cost when recovering phosphorus and iron elements is reduced.

[0058] It should be noted that when the discharged battery is crushed in the embodiment of the present application, the crushing degree is low, and the content of impurities such as copper and aluminum mixed in the battery powder after screening with a 10-40 mesh screen is as low as possible.

[0059] In an optional embodiment, the first screen oversize material is mixed with N-methyl pyrrolidone and water under ultrasonic conditions to obtain a mixed solution, the mixed solution is screened with an 80-120 mesh screen to obtain second screen undersize material containing battery powder and second screen oversize material containing copper, aluminum and separators;

[0060] The second screen oversize material is fed into a shaking table, and a copper-containing material is obtained from the concentrate port, and an aluminum-containing and separator-containing mixed material is obtained from the tailings port;

[0061] The aluminum-containing and separator-containing mixed material is dried and air separated to obtain an aluminum-containing material and a separator-containing material.

[0062] When the battery powder in the first screen oversize material is separated, N-methyl pyrrolidone is added to the water, and ultrasonic is used at the same time, which is beneficial to the falling of the battery powder adhered to the copper and aluminum and separators, and thus improves the separation effect of the battery powder.

[0063] The lithium iron phosphate battery powder on the copper and aluminum material is stripped in multiple steps. First, the battery powder on most of the pole pieces is removed by preliminary crushing and scattering. The remaining small amount of battery powder on the copper and aluminum is separated from the copper and aluminum material after being added with NMP and treated by ultrasonic wave, which can improve the powdering rate of the lithium iron phosphate battery powder in the recovery process.

[0064] In an optional embodiment, the amount of N-methyl pyrrolidone is 1wt%-5wt% of the mixed solution, and specifically can be 1wt%, 2wt%, 3wt%, 4wt%, 5wt% or any value between 1wt% and 5wt%. In theory, increasing the amount of N-methyl pyrrolidone is beneficial to the falling of the battery powder from the surface of the copper and aluminum and separators, but too much N-methyl pyrrolidone will increase the amount of N-methyl pyrrolidone mixed in the battery powder, and will also cause waste of N-methyl pyrrolidone.

[0065] In an optional embodiment, the flotation step includes once roughing, four times cleaning and twice scavenging, and adjusting agent, foaming agent and collector are added in the roughing, cleaning and scavenging steps;

[0066] In the selection process, the second middling obtained in the second selection process can be returned to the first selection process as the raw material to be selected, the third middling obtained in the third selection process can be returned to the second selection process as the raw material to be selected, and the fourth middling obtained in the fourth selection process can be returned to the third selection process as the raw material to be selected.

[0067] In the scavenging process, the first middling obtained in the first scavenging process can be returned to the roughing process as the raw material to be selected, and the second middling obtained in the second scavenging process can be returned to the first scavenging process as the raw material to be selected.

[0068] In the flotation process, the frother can increase the amount of foam, which is beneficial to the flotation; and the regulator used is beneficial to the separation of graphite, and the graphite is effectively captured by the graphite collector. The production cost of the recovered graphite material from the waste lithium iron phosphate battery negative electrode graphite material is low, and the purity of the recovered graphite material is high, which can greatly reduce the production cost of the lithium iron phosphate battery.

[0069] In an optional embodiment, the regulator is at least one of sodium carboxymethyl cellulose, sodium humate, and sulfuric acid, and the amount used is 50 g / t-300 g / t; too much amount will not significantly improve the separation effect of graphite, and will also cause waste of raw materials.

[0070] In an optional embodiment, the frother is 2# oil, and the amount used is 20 g / t-200 g / t; too much amount will not significantly improve the separation effect of graphite, and will also cause waste of raw materials.

[0071] In an optional embodiment, the collector is kerosene, and the amount used is 20 g / t-500 g / t; too much amount will not significantly improve the separation effect of graphite, and will also cause waste of raw materials.

[0072] In an optional embodiment, the method further comprises separating the graphite from the flotation froth and performing graphitization treatment on the graphite to obtain a battery-grade graphite product, and the graphitization treatment comprises mixing the separated graphite with an additive at a mass ratio of 2-5 and then performing heat treatment at a temperature of 800-1200°C, and specifically, the mass ratio of the graphite to the additive is 2, 3, 4, 5, or any value between 2 and 5.

[0073] In an optional embodiment, the additive is at least one of pitch, phenolic resin, and glucose.

[0074] The graphitization treatment is beneficial to improving the electrical performance of the battery in which the graphite is applied. In some embodiments, in order to improve the purity of the graphite, the graphite separated from the flotation froth can be subjected to acid leaching to remove acid-soluble impurities, thereby further improving the electrical performance of the battery in which the graphite is applied.

[0075] In an alternative embodiment, the flotation tailings containing the phosphorus-iron material are mixed with sulfuric acid, and after adjusting the pH value to 0.5-2, solid-liquid separation is performed, followed by adding H2O2 to adjust the pH value to 3.5-7, and after solid-liquid separation, the phosphorus-iron solution is obtained; after treatment with H2O2 and sulfuric acid, part of the impurities contained therein can be removed.

[0076] In an alternative embodiment, the mass ratio of H2O2 to flotation tailings is 0.08-0.15.

[0077] The features and performances of the present application are further described in detail below in combination with examples.

[0078] Example 1

[0079] This example provides a method for recycling battery powder in an entire chain, as shown in Figure 1 The method mainly includes the following steps:

[0080] (1) Pretreatment: the waste lithium iron phosphate battery powder is discharged, crushed, and preliminarily dispersed using a dispersing machine, to obtain a material with a graphite C content of 43.36wt%, a Li content of 1.79wt%, a Fe content of 13.28wt%, a P content of 8.18wt%, a Cu content of 14.10wt%, and an Al content of 4.10wt%, and then the crushed battery material is sieved using a 20-mesh sieve, and the oversize material is large block copper aluminum, plastic diaphragm, and battery powder adhered to the copper aluminum, and the undersize material is battery powder and a small amount of fine particle copper aluminum.

[0081] (2) The oversize material of step (1) is added to a stirring barrel with an ultrasonic generator, and NMP is added thereto, wherein the solid solution amount of the material in the stirring barrel is 200g / L, the concentration of NMP is 10g / L, the stirring time is 15min, and after ultrasonic treatment, the material is sieved using a 100-mesh sieve, and the undersize material is battery powder, and the oversize material is copper aluminum and diaphragm.

[0082] (3) The oversize material of step (2) is fed into a shaking table, copper is obtained from the concentrate port, and Al and diaphragm are obtained from the tailings port, and the tailings are dried and fed into a wind separator to separate Al and plastic diaphragm.

[0083] (4) The undersize material of step (1) is fed into a Nelson concentrator, the backflush water flow rate is adjusted to 24m / s, and the barrel speed is controlled to 400rpm, and Al and battery powder are discharged from the tailings port, and Cu is discharged from the concentrate port.

[0084] (5) The tailings obtained in step (4) are subjected to centrifugal gravity separation again, the backflush water flow rate of the Nelson concentrator is adjusted to 15m / s, and the barrel speed is controlled to 520rpm, fine particle Al metal is obtained from the concentrate port, and lithium iron phosphate battery powder is obtained from the tailings port.

[0085] (6) The battery powder in step (5) is subjected to pressure filtration, and the battery powder after pressure filtration is dried at 130°C. After drying, iron sulfate, H2O2 and sulfuric acid are added to the battery powder, wherein the molar ratio of sulfate ions to lithium ions is 1.1:1, the molar ratio of sulfuric acid to iron sulfate is 1:1, and the mass ratio of H2O2 to battery powder is 0.1:1. The mixed material is fed into a rotary kiln, an air atmosphere is set, the roasting temperature is 400°C, and the roasting time is 60 min.

[0086] (7) The material after roasting in step (6) is placed in a stirring barrel, pure water is added to the stirring barrel, the liquid-solid ratio is set to 5:1, the stirring speed is set to 500 rpm, and the stirring time is 1 h. After stirring, the stirred battery powder material is subjected to pressure filtration, the filtrate is a lithium-containing filtrate, and the filter residue is a lithium-extracted lithium iron phosphate battery powder.

[0087] (8) The battery powder in step (7) is fed into a flotation machine for flotation. The flotation process is one roughing, four cleanings and two scavengings. During the flotation process, 150 g / t of adjusting agent (CMC and sulfuric acid in a mass ratio of 1:2), 2# oil (100 g / t) as a foaming agent, and 280 g / t of coal oil as a collector are sequentially added. The specific process is shown in FIG. 2. The graphite is separated from the lithium-extracted battery powder, and the foam obtained by flotation is the graphite-containing product. The flotation tailings contain lithium-extracted phosphorus iron material. Figure 2

[0088] (9) The recovered graphite raw material in step (8) is graphitized, and after further acid leaching and purification treatment, a certain proportion of additives (mainly pitch, phenolic resin and glucose in a mass ratio of 6:1:1) is added to the graphite, the mass ratio m(graphite):m(additive) is 5, and the graphite is roasted at 900°C to optimize the surface morphology of the recovered graphite and obtain a battery-grade graphite product.

[0089] (10) The lithium-extracted phosphorus iron material recovered in step (8) is added to a stirring tank, sulfuric acid is added to control the pH value to 1.6, impurities are removed by filtration, H2O2 is added to the filtrate to adjust the pH value to 5.4, and the phosphorus iron is obtained after solid-liquid separation.

[0090] Example 2

[0091] The embodiment provides a full-chain integrated battery powder recycling method, which is mainly different from example 1 in that the oxygen roasting temperature in step (6) is 350°C.

[0092] Example 3

[0093] The embodiment provides a full-chain integrated battery powder recycling method, which is mainly different from example 1 in that the oxygen roasting temperature in step (6) is 450°C. ​

[0094] Example 4

[0095] The present embodiment provides a method for recycling battery powder in a full-chain integrated manner, which mainly comprises the following steps:

[0096] (1)-(3) are the same as in Example 1.

[0097] (4) The undersize material in step (1) is fed into a Nelson concentrator, the backflush water flow rate is adjusted to 22 m / s, the barrel speed is controlled to 300 rpm, Al and battery powder are discharged from the tailings port, and Cu is discharged from the concentrate port.

[0098] (5) The tailings obtained in step (4) are subjected to centrifugal reselection again, the backflush water flow rate of the Nelson concentrator is adjusted to 18 m / s, the barrel speed is controlled to 400 rpm, fine-grained Al metal is obtained from the concentrate port, and lithium iron phosphate battery powder is obtained from the tailings port.

[0099] (6) The battery powder in step (5) is subjected to pressure filtration, and the battery powder after pressure filtration is dried at 130°C, then iron sulfate, H2O2 and sulfuric acid are added to the battery powder, the molar ratio of sulfate and lithium ion is 0.5:1, the molar ratio of sulfuric acid and iron sulfate is 0.5:1, and the mass ratio of H2O2 and battery powder is 0.1:1, the mixed material is fed into a rotary kiln, the atmosphere is set to air atmosphere, the roasting temperature is 400°C, and the roasting time is 2h.

[0100] (7) The material after roasting in step (6) is placed in a stirring barrel, pure water is added to the stirring barrel, the liquid-solid ratio is set to 3:1, the stirring speed is set to 500 rpm, and the stirring time is 50 min, after stirring, the stirred battery powder material is subjected to pressure filtration, the filtrate is a lithium-containing filtrate, and the filter residue is lithium-extracted lithium iron phosphate battery powder.

[0101] (8) The battery powder in step (7) is fed into a flotation machine for flotation, the flotation process is one roughing, four cleanings and two scavengings, as shown in the specific process shown in Figure 2 , graphite is separated from the lithium-extracted battery powder, the foam obtained by flotation is a graphite-containing product, and the flotation tailings contain lithium-extracted phosphorus iron material.

[0102] (9) The recovered graphite raw material in step (8) is graphitized, and after further acid leaching and purification treatment, a certain proportion of additives (mainly pitch and phenolic resin and glucose in a mass ratio of 6:1:1) is added to the graphite, the mass ratio m(graphite):m(additive) is 5, and the graphite is calcined at 900°C to obtain a battery-grade graphite product.

[0103] The iron phosphate material recovered in step (8) is added to a stirring tank, sulfuric acid is added, the pH value is controlled to 1.6, impurities are removed by filtration, H2O2 is added to the filtrate to adjust the pH value to 5.4, and solid-liquid separation is performed to obtain iron phosphate

[0104] Example 5

[0105] The present embodiment provides a method for recycling battery powder in a full-chain integrated manner, which mainly comprises the following steps:

[0106] (1)-(3) are the same as in Example 1.

[0107] (4) The undersize material in step (1) is fed into a Nelson concentrator, the backflush water flow rate is adjusted to 30 m / s, the cylinder rotation speed is controlled to 300 rpm, Al and battery powder are discharged from the tailings port, and Cu is discharged from the concentrate port.

[0108] (5) The tailings obtained in step (4) are subjected to centrifugal reselection again, the backflush water flow rate of the Nelson concentrator is adjusted to 12 m / s, the cylinder rotation speed is controlled to 800 rpm, fine-grained Al metal is obtained from the concentrate port, and lithium iron phosphate battery powder is obtained from the tailings port.

[0109] (6) The battery powder in step (5) is subjected to pressure filtration, the pressure-filtered battery powder is dried at 130°C, and then iron sulfate, H2O2 and sulfuric acid are added to the dried battery powder, wherein the molar ratio of sulfate ions to lithium ions is 1.5:1, the molar ratio of sulfuric acid to iron sulfate is 1.5:1, and the mass ratio of H2O2 to battery powder is 0.1:1, the mixed material is fed into a rotary kiln, an air atmosphere is set, the roasting temperature is 400°C, and the roasting time is 0.5 h.

[0110] (7) The material after roasting in step (6) is placed in a stirring barrel, pure water is added to the stirring barrel, the liquid-solid ratio is set to 7:1, the stirring rotation speed is set to 500 rpm, the stirring time is 70 min, after stirring, the stirred battery powder material is subjected to pressure filtration, the filtrate is a lithium-containing filtrate, and the filter residue is lithium-extracted lithium iron phosphate battery powder.

[0111] (8) The battery powder in step (7) is fed into a flotation machine for flotation, the flotation process is one roughing, four cleanings and two scavengings. During the flotation process, the adjusting agent sodium humate 300 g / t, the frother 2# oil (50 g / t), and the collector kerosene (500 g / t) are sequentially added, as shown in the specific process Figure 2 , the graphite is separated from the lithium-extracted battery powder, the foam obtained by flotation is the graphite-containing product, and the flotation tailings contain the lithium-extracted iron phosphate material.

[0112] (9) The graphite raw material recovered in step (8) is graphitized, and after further acid leaching purification treatment, a certain proportion of additives (mainly pitch and phenolic resin and glucose in a mass ratio of 6:1:1) is added to the graphite, the mass ratio m (graphite) : m (additives) = 5, and roasting is carried out at 900°C to obtain a battery-grade graphite product.

[0113] (10) The iron phosphate material recovered in step (8) is added to a stirring tank, sulfuric acid is added, the pH value is controlled to 1.6, impurities are removed by filtration, H2O2 is added to the filtrate to adjust the pH value to 5.4, and iron phosphate is obtained after solid-liquid separation.

[0114] Comparative Example 1

[0115] This comparative example provides a full-chain integrated battery powder recycling method, which is mainly different from Example 1 in that the lithium iron phosphate battery powder in this comparative example is not subjected to aerobic roasting treatment, and the mixture of iron sulfate, H2O2 and sulfuric acid is added to the battery powder and then step (7) is carried out.

[0116] Comparative Example 2

[0117] This comparative example provides a full-chain integrated battery powder recycling method, which is mainly different from Example 1 in that steps (4) and (5) are not carried out in this comparative example, the undersize material in step (1) is dried at 130°C, and then subjected to oxidative roasting, and the remaining steps are the same as in Example 1.

[0118] Comparative Example 3

[0119] This comparative example provides a full-chain integrated battery powder recycling method, which is mainly different from Example 1 in that in step (6), iron sulfate, H2O2 and sulfuric acid are not added to the battery powder.

[0120] Comparative Example 4

[0121] This comparative example provides a full-chain integrated battery powder recycling method, which is mainly different from Example 1 in that in step (6), H2O2 and sulfuric acid are not added to the battery powder.

[0122] Comparative Example 5

[0123] This comparative example provides a full-chain integrated battery powder recycling method, which is mainly different from Example 1 in that in step (6), iron sulfate and sulfuric acid are not added to the battery powder.

[0124] Comparative Example 6

[0125] This comparative example provides a full-chain integrated battery powder recycling method, which is mainly different from Example 1 in that in step (6), iron sulfate and H2O2 are not added to the battery powder.

[0126] Comparative Example 7

[0127] The present comparative example provides a method for recycling battery powder in a full chain integration. The main difference from Example 1 is that in step (6), no iron sulfate, H2O2 and sulfuric acid are added to the battery powder, and the roasting atmosphere is nitrogen.

[0128] The C content and C recovery rate in the battery-grade graphite product obtained in the examples and comparative examples, and the Li recovery rate in the lithium extraction step, were measured, and the results are shown in Table 1.

[0129] Table 1 Comparison of nickel, cobalt, manganese and iron recovery rate data of examples and comparative examples

[0130]

[0131] The battery-grade graphite product obtained in the examples and comparative examples was respectively subjected to pulping, coating, assembly with LiCoO2 cathode sheet, and pressing into a button cell, and the cell was tested under the conditions of a charging voltage of 4.2 V and a current of 0.1 C. The test results are shown in Table 2.

[0132] Table 2 Electrochemical performance table of graphitized products of examples and comparative examples

[0133]

[0134]

[0135] As can be seen from Tables 1-2, it can be seen from Examples 1-3 that by treating the lithium iron phosphate battery by the method of the present application, the lithium recovery rate can reach 94.43% or more, the graphite recovery rate can reach 93.12% or more, and the carbon content of the recovered graphite product is relatively high, with a carbon content of 92.47% or more. After graphitization treatment, the battery-grade graphite has high electrochemical performance, with a first charge-discharge efficiency of 90.16% or more, and a battery capacity retention rate of 96.15% or more after 100 cycles at 0.1 C, meeting the commercial specifications. In addition, the Cu and Al content of the residual iron phosphate slag after multiple recoveries is greatly reduced, and the iron phosphate slag can become a raw material for producing positive electrode materials for lithium iron phosphate batteries after impurity removal at a low cost.

[0136] As can be seen from the comparison of Example 1 and Examples 2-3, in addition to affecting the recovery rate of lithium, the oxidation roasting temperature in the process also affects the carbon content and recovery rate of the graphite product recovered after flotation. If the roasting temperature is too low, the lithium leaching rate will decrease, and the carbon content of the graphite product will also decrease. If the oxidation roasting temperature is too high, the lithium leaching rate will decrease.

[0137] From the comparison of example 1 and examples 4-5, it can be seen that adjusting the water flow rate and the barrel speed during the centrifugal gravity separation in the process will affect the separation effect of copper and aluminum from the battery powder, and suitable process conditions can better reduce the content of copper and aluminum in the battery powder.

[0138] From example 1 and comparative example 1, it can be seen that oxidative roasting can enhance the separation effect between the positive and negative electrode materials, and without oxygen roasting, the separation and recovery of Li and carbon elements cannot be performed.

[0139] From example 1 and comparative example 2, it can be seen that increasing the centrifugal gravity separation process can greatly reduce the content of Cu and Al in the lithium iron phosphate battery powder entering the wet lithium extraction process, and greatly reduce the subsequent phosphorus iron slag impurity removal and recycling cost.

[0140] From example 1 and comparative example 3, it can be seen that without adding iron sulfate, hydrogen peroxide and sulfuric acid in step (7), the Li element in the lithium iron phosphate battery powder cannot be preferentially leached and recovered, but still enters the flotation tailings, i.e. phosphorus iron slag, together with P and Fe elements. From comparative examples 4-7, it can also be seen that iron sulfate, hydrogen peroxide and sulfuric acid have a great influence on the lithium extraction and graphite recovery.

[0141] From comparative example 3 and comparative example 7, it can be seen that compared with nitrogen atmosphere, air atmosphere is more conducive to removing the carbon coating film and long carbon chain substances such as organic binder on the surface of the positive electrode material in the battery powder, and the positive and negative electrode sheet powder treated in air atmosphere has a larger difference in floatability, which is more conducive to flotation separation to obtain a higher quality graphite product.

[0142] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for integrated recycling of battery powder across the entire supply chain, characterized in that, include: Aerobic roasting involves calcining a mixture of battery powder, ferric sulfate, H2O2, and sulfuric acid to obtain a roasted material. The battery powder is obtained by discharging and crushing a lithium iron phosphate battery to remove copper, aluminum, and the separator. Lithium extraction by water immersion involves mixing the roasted material with water to extract lithium and perform solid-liquid separation, resulting in lithium-containing filtrate and lithium-extracted battery powder. Flotation involves using a flotation machine to float lithium-extracted battery powder, resulting in flotation foam containing graphite and flotation tailings containing phosphate iron materials. The preparation of the battery powder includes: Pretreatment involves discharging and crushing the lithium iron phosphate battery to obtain crushed material. Then, the crushed material is screened using a 10-40 mesh sieve to obtain primary undersize material containing battery powder and fine copper and aluminum particles, and primary oversize material containing copper, aluminum, and plastic separator. The primary undersize material is subjected to a first centrifugal gravity separation using a mineral processing machine. A mixture of battery powder and aluminum is obtained at the tailings outlet, and copper-containing material is obtained at the concentrate outlet. The backwash water flow rate of the mineral processing machine in the first centrifugal gravity separation is 20m / s-30m / s, and the cylinder rotation speed is 300rpm-700rpm. The mixture of battery powder and aluminum is subjected to a second centrifugal gravity separation using a mineral processing machine. Battery powder is obtained from the tailings outlet, and aluminum is obtained from the concentrate outlet. The backwash water flow rate of the mineral processing machine in the second centrifugal gravity separation is 12m / s-18m / s, and the cylinder rotation speed is 400rpm-800rpm. The solids in the battery-containing powder are separated and dried to obtain the battery powder.

2. The method for integrated full-chain battery powder recycling according to claim 1, characterized in that, The aerobic roasting temperature is 300℃-500℃, and the time is 0.5h-2h.

3. The method for integrated full-chain battery powder recycling according to claim 1, characterized in that, The molar ratio of sulfate to lithium ions in the mixture is (0.5-1.5):

1.

4. The method for integrated full-chain battery powder recycling according to claim 1, characterized in that, The molar ratio of sulfuric acid to ferric sulfate in the mixture is (0.5-1.5):

1.

5. The method for integrated full-chain battery powder recycling according to claim 1, characterized in that, The mass ratio of H2O2 to battery powder in the mixture is (0.1-0.2):

1.

6. The method for integrated full-chain battery powder recycling according to claim 1, characterized in that, In the water immersion lithium extraction process, the liquid-to-solid ratio in the liquid before lithium extraction is (3~7):1ml / g, and the lithium extraction time is 50min-70min.

7. The method for integrated full-chain battery powder recycling according to claim 1, characterized in that, The material on the primary sieve is mixed with N-methylpyrrolidone and water under ultrasonic conditions to obtain a mixture. The mixture is then sieved using an 80-120 mesh sieve to obtain a secondary undersize material containing battery powder and a secondary oversize material containing copper, aluminum and a separator. The material over the secondary screen is fed into a shaking table, and copper-containing material is obtained at the concentrate outlet, while a mixture containing aluminum and a diaphragm is obtained at the tailings outlet. The mixture containing aluminum and the diaphragm is dried and air-separated to obtain aluminum-containing material and diaphragm-containing material.

8. The method for integrated full-chain battery powder recycling according to claim 7, characterized in that, The amount of N-methylpyrrolidone used is 1wt%-5wt% of the mixture.

9. The method for integrated full-chain battery powder recycling according to claim 1, characterized in that, The flotation process includes one roughing, four cleaning, and two scavenging processes, all of which involve the addition of modifiers, frothers, and collectors.

10. The method for integrated full-chain battery powder recycling according to claim 9, characterized in that, The modifier is selected from at least one of sodium carboxymethyl cellulose, sodium humate, and sulfuric acid, and the dosage is 50g / t-300g / t.

11. The method for integrated full-chain battery powder recycling according to claim 9, characterized in that, The foaming agent is No. 2 oil, and the dosage is 20g / t-200g / t.

12. The method for integrated full-chain battery powder recycling according to claim 9, characterized in that, The collector is kerosene, and the dosage is 20g / t-500g / t.

13. The method for integrated full-chain battery powder recycling according to claim 1, characterized in that, It also includes separating the graphite from the flotation foam and performing graphitization treatment to obtain battery-grade graphite products. The graphitization treatment includes mixing the separated graphite with additives at a mass ratio of 2-5 and then performing heat treatment at 800-1200°C.

14. The method for integrated full-chain battery powder recycling according to claim 13, characterized in that, The additive is at least one of asphalt, phenolic resin and glucose.

15. The method for integrated full-chain battery powder recycling according to claim 1, characterized in that, Flotation tailings containing ferric phosphate are mixed with sulfuric acid, and the pH is adjusted to 0.5-2 before solid-liquid separation. Then, H2O2 is added to adjust the pH to 3.5-7. After solid-liquid separation, ferric phosphate solution is obtained.

16. The method for integrated full-chain battery powder recycling according to claim 15, characterized in that, The mass ratio of H2O2 to flotation tailings is 0.08-0.15.

Images