Method for recycling lithium from waste lithium ion batteries and regenerating ternary precursor

Abstract

The application discloses a method for recycling lithium from waste lithium ion batteries and regenerating ternary precursors. The method for recycling lithium from waste lithium ion batteries comprises the following steps: obtaining positive and negative mixed electrode materials by industrial inert crushing and grading of the waste lithium ion batteries; obtaining a calcination product by in-situ self-reduction calcination of the positive and negative mixed electrode materials; uniformly mixing the calcination product with deionized water to prepare a slurry, and then placing the slurry in an ultrasonic reactor for ultrasonic-assisted water immersion, and obtaining a lithium-containing filtrate and a water immersion residue through filtration. The method can selectively recycle lithium and valuable metals in the waste lithium ion batteries without pre-sorting the waste lithium ion batteries, and has the advantages of high recovery rate of lithium and valuable metals, short process, good product quality, and economic and environmental protection.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of waste lithium-ion battery recycling, and particularly relates to a method for recycling lithium from waste lithium-ion batteries and regenerating ternary precursors. BACKGROUND

[0002] With the improvement of energy density and efficiency, lithium-ion batteries are widely used in electric vehicles (EV), energy, medical, military and other fields. At the same time, if the waste lithium-ion batteries are not properly treated, they will bring serious safety hazards due to the use of toxic substances and heavy metals, which not only harm the environment but also pose a great threat to human health. In addition, the rapid development of the global electric vehicle market has led to a rapid increase in demand for ternary lithium-ion batteries, causing the prices of nickel, cobalt and manganese minerals to rise, which makes the recycling of waste lithium-ion batteries extremely urgent. One of the main challenges of recycling is to achieve efficient and low-energy consumption reuse of battery materials. The common methods for recycling waste lithium batteries are hydrometallurgy, pyrometallurgy and dry recovery.

[0003] At present, the recycling of waste lithium-ion batteries in China mainly adopts the wet recovery method, and the dry recovery method is used as a supporting process for the wet recovery method. The typical process is the pretreatment of waste lithium-ion batteries, including discharging, disassembly, crushing, sorting and other steps. The positive and negative electrode powders obtained after sorting are subjected to reduction acid leaching to make lithium, nickel, cobalt, manganese and other elements enter the solution. The leaching solution is purified and then subjected to extraction process to obtain pure solution of nickel, cobalt, manganese and copper and produce corresponding products, or directly produce ternary precursor products. However, there is no uniform standard for the size and structure specifications of the batteries at present, and the automatic sorting technology and equipment are not very mature, resulting in serious loss of valuable metals in the pre-sorting process, and high content of copper and aluminum impurities in the positive and negative electrode powders. Therefore, it is of great significance to develop a new method without pre-sorting under this background.

[0004] The pyrometallurgical-hydrometallurgical combined process is the mainstream technology for recycling waste lithium batteries abroad, which mainly includes three important links: the pretreatment of waste lithium batteries, the leaching of valuable metals, and the extraction and purification of target metals in the leaching solution. Chinese patent CN115417434 A discloses a method for recycling valuable metals from waste lithium-ion battery black powder by carbon thermal reduction and preparing lithium carbonate products, which comprises the following steps: adding lithium-containing battery waste to carbon-containing material as a reducing agent to obtain a mixture, calcining the mixture under a carbon dioxide atmosphere, and stirring and water leaching the calcined material in a high-pressure reaction container by introducing carbon dioxide gas to realize lithium recovery. The lithium carbonate obtained by carbon thermal reduction is subjected to pressurized hydrogenation, filtration and adsorption impurity removal, and evaporation crystallization processes to obtain lithium carbonate products. The method provided by the present application has the following disadvantages: (1) long process flow, complex operation, and high equipment requirements; (2) complex impurity removal process, high recovery cost, and high lithium loss rate; (3) high calcination temperature and high energy consumption.

[0005] At the same time, lithium ions are prone to deposit on the negative electrode sheet during use, especially for waste lithium ion batteries with a capacity of less than 50%. In addition, lithium deposition on the negative electrode sheet is also very serious after misuse under high and low temperature, overcharge and overdischarge or other special conditions. Through disassembly of the lithium ion battery, it can be found that there are a large number of yellow lithium single elements on the surface of the negative electrode sheet, and oxidation occurs rapidly in the air. If the lithium resource deposited on the negative electrode sheet cannot be recovered by a reasonable method, not only the lithium resource is wasted, but also the environment is polluted.

[0006] In terms of nickel-cobalt-manganese recovery, chemical precipitation method, ion exchange method, solvent extraction method and other methods are usually used for separation and recovery. If the nickel-cobalt-manganese ternary precursor is prepared by direct coprecipitation, the impurities in the solution must be removed deeply before precipitation, which is very difficult. The advantage of wet leaching solution for regenerating nickel-cobalt-manganese ternary precursor is to avoid the separation steps such as extraction and precipitation after leaching, maximize the comprehensive recovery efficiency of metals, realize the closed loop of the recovery process and the resource regeneration of the positive electrode material. At the same time, the simple and effective process flow makes the wet regeneration have popularization value in industrial production.

[0007] In summary, it is of great significance to develop an efficient method for recovering lithium from waste lithium ion batteries and regenerating ternary precursors. SUMMARY

[0008] The purpose of the present application is to overcome the above technical deficiencies, and to provide a method for recovering lithium from waste lithium ion batteries and regenerating ternary precursors, which solves the technical problems of long process flow, high lithium loss rate and complex impurity removal process in the prior art method for recovering lithium and valuable metals from waste lithium ion batteries.

[0009] In a first aspect, the present application provides a method for recovering lithium from waste lithium ion batteries, comprising the following steps:

[0010] The waste lithium ion battery is subjected to industrial inert pulverization and grading process to obtain positive and negative electrode mixed electrode materials;

[0011] The positive and negative electrode mixed electrode materials are subjected to in-situ self-reduction roasting to obtain a roasting product;

[0012] The roasting product is uniformly mixed with deionized water to form a slurry, and then is placed in an ultrasonic reactor for ultrasonic-assisted water immersion. After filtration, a lithium-containing filtrate and a water leaching residue are obtained.

[0013] In a second aspect, the present application provides a method for regenerating ternary precursors from waste lithium ion batteries, comprising the following steps:

[0014] The water leaching residue obtained in the first aspect of the present application is subjected to ball milling slurry treatment to obtain a slurry liquid, and then the slurry liquid is subjected to magnetic separation to obtain a magnetic separation concentrate and a magnetic separation tailing;

[0015] The magnetic separation concentrate is subjected to acid leaching, and a metal leaching liquid is obtained through filtration, and then an oxidizing agent and an alkaline substance are added to the metal leaching liquid for impurity removal, the final pH value of the solution is maintained at 4.5-5.5, and a post-impurity-removal liquid is obtained through filtration;

[0016] The proportions of nickel, cobalt and manganese in the post-impurity-removal liquid are adjusted to reach the proportions of nickel, cobalt and manganese in the target ternary positive electrode material, and then an ammonia water solution and a sodium hydroxide solution are added for co-precipitation reaction, and finally a ternary positive electrode material precursor is prepared through filtration, washing and drying.

[0017] Compared with the prior art, the present application has the following beneficial effects:

[0018] The process of the present application can selectively recover lithium and valuable metals (nickel, cobalt and manganese) from waste lithium ion batteries without pre-sorting the waste lithium ion batteries, has high recovery rate of lithium and valuable metals (nickel, cobalt and manganese), short process flow, good product quality, and is economical and environmentally friendly. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 A process flow chart of an embodiment of the method for recovering lithium from waste lithium ion batteries provided by the present application;

[0020] Figure 2 A process flow chart of an embodiment of the method for regenerating and preparing a ternary precursor from waste lithium ion batteries provided by the present application;

[0021] Figure 3 A graph showing the relationship between different ultrasonic times and lithium recovery rate for positive and negative electrode mixed electrode material powders under ultrasonic-assisted water leaching conditions;

[0022] Figure 4 A phase analysis and microstructure observation chart of the refined lithium carbonate powder obtained in Example 2 of the present application;

[0023] Figure 5 A phase analysis of the nickel-cobalt-manganese ternary precursor powder obtained in Example 2 of the present application;

[0024] Figure 6 A microstructure observation chart of the nickel-cobalt-manganese ternary precursor powder obtained in Example 2 of the present application. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical scheme and advantages of the present application clearer and more apparent, the present application will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0026] As described previously, the traditional dry sorting-wet recovery combined process is faced with many technical problems to be solved, including the following: (1) in the pretreatment sorting step, the active material and copper-aluminum foil are seriously inter-contained, and the valuable components are easy to be lost; (2) the ternary positive electrode material has stable structure, and cobalt and manganese in the material exist in high valence form, so that the leaching conditions are relatively harsh, and expensive reducing agent needs to be added; (3) in the acid leaching process, aluminum and iron impurities enter the leaching solution, and the solution purification process is complex; (4) the "lithium extraction after recovery" process is adopted, and the lithium recovery rate is generally only about 50%, which causes great waste of lithium resources; (5) when the positive electrode material reduction roasting-water leaching lithium recovery process is adopted, the lithium recovery rate can only reach 80%, which is mainly caused by the adsorption of residual reducing agent material on lithium ions after roasting; (6) if the lithium resources deposited on the negative electrode sheet cannot be recovered by a reasonable method, not only the lithium resources are wasted, but also the environment is polluted; (7) the solvent extraction process for separating manganese, cobalt, nickel and lithium has long process flow, many stages, and large loss of valuable metals. In order to solve the above problems, the present application is proposed.

[0027] Please refer to Figure 1 , in the first aspect, the present application provides a method for recovering lithium from waste lithium ion batteries, comprising the following steps:

[0028] S1, the waste lithium ion battery is crushed by industrial inert powdering-classification process to obtain positive and negative electrode mixed electrode material;

[0029] S2, the positive and negative electrode mixed electrode material is subjected to in-situ self-reduction roasting to obtain a roasting product;

[0030] S3, the roasting product is uniformly mixed with deionized water to prepare a slurry, and then is placed in an ultrasonic reactor for ultrasonic-assisted water leaching, and a lithium-containing filtrate and a water leaching residue are obtained after filtration.

[0031] The process of the application does not need pre-sorting of waste lithium ion batteries, only needs to be converted into positive and negative mixed electrode materials through a simple industrial inert crushing-classification process, and uses graphite, separators, organic binders and the like in the positive and negative mixed electrode materials as a reducing agent for in-situ self-reduction roasting, so as to realize pyrolysis removal of organic matter in the positive and negative mixed electrode materials, dissociation of the positive electrode material, reduction of high-valence transition metals and conversion of deposited lithium oxide on the negative electrode sheet in one step, and then realizes efficient leaching of lithium resources through ultrasonic-assisted water leaching of the roasting product, so as to selectively recover lithium in the waste lithium battery. At the same time, by using the mechanical effect, cavitation effect, thermal effect and chemical effect brought by ultrasonic waves, the leaching rate is higher, the leaching rate is faster, and the process is more environmentally friendly and energy-saving than the conventional water leaching, which can play a strengthening role in the wet recovery link, and help to realize low energy consumption, low pollution, multiple recovery types, high separation purity and recovery of valuable metals in lithium batteries. In the process of recovering lithium by ultrasonic-assisted water leaching, the effect of ultrasonic waves can also promote the separation of transition metal oxides or elements and the remaining graphite to a certain extent, and create certain favorable conditions for subsequent grinding-magnetic separation. The recovery rate of lithium and valuable metals (nickel, cobalt and manganese) in the application is high, the process is short, the product quality is good, and it is economical and environmentally friendly.

[0032] In the embodiment, the inert gas selected in the industrial inert crushing-classification process is nitrogen or carbon dioxide.

[0033] In the embodiment, the particle size of the positive and negative mixed electrode material is less than 1 mm; preferably, the particle size of the positive and negative mixed electrode material is 90% of -0.2 mm.

[0034] In the embodiment, the main chemical components of the waste ternary lithium ion battery positive and negative mixed electrode material are: Li 3%-5%, Ni 10%-15%, Co 5%-10%, Mn 12-15%, Cu 5%-10%, Al 5%-10%, C 40%-45%, Fe 0-1%, and the balance is other elements and loss on ignition.

[0035] In the embodiment, in the process of in-situ self-reduction roasting, the roasting temperature is 600-700 DEG C, the roasting time is 1-2 h, and the roasting atmosphere is nitrogen or carbon dioxide. Under this roasting condition, the lithium recovery rate is the highest.

[0036] In the present embodiment, the liquid-solid ratio of the slurry in the ultrasonic-assisted water immersion process is 10-25 mL / g, preferably 15-20 mL / g; the power of the ultrasonic wave is 100-500 W, preferably 200-500 W, more preferably 400-450 W. The present application selects a relatively high ultrasonic wave power, which is beneficial to reducing the adsorption of carbonaceous materials in the leaching residue on lithium ions in the leaching solution, and is also beneficial to promoting the dissolution of the deposited lithium oxide on the negative electrode material, so as to improve the recovery rate of lithium; however, the ultrasonic wave power should not be too high, otherwise the purity of lithium carbonate will decrease. The leaching temperature is 20-35 DEG C, preferably 25-30 DEG C; the leaching time is 5-30 min, preferably 20-25 min.

[0037] In the present embodiment, the method for recovering lithium from waste lithium ion batteries further comprises the following steps:

[0038] S4, after the lithium-containing filtrate is evaporated and concentrated, a theoretical amount of 1.0-1.5 times of a carbonate precipitant is added, and a crude lithium carbonate is obtained by filtration, followed by water washing of the crude lithium carbonate, and drying to obtain refined lithium carbonate.

[0039] In the present embodiment, the lithium content in the lithium-containing filtrate after evaporation and concentration is 20-30 g / L.

[0040] In the present embodiment, the lithium content in the lithium-containing filtrate after evaporation and concentration is 20-30 g / L.

[0041] In the present embodiment, the lithium content in the lithium-containing filtrate after evaporation and concentration is 20-30 g / L.

[0042] In the present embodiment, the lithium content in the lithium-containing filtrate after evaporation and concentration is 20-30 g / L.

[0043] Please refer to Figure 2 , in a second aspect, the present application provides a method for preparing a ternary precursor from waste lithium ion batteries, comprising the following steps:

[0044] S5, the water immersion residue obtained in the above step S3 is subjected to ball milling and slurry treatment to obtain a slurry, and then the slurry is subjected to magnetic separation to obtain a magnetic separation concentrate and a magnetic separation tailing; this step can realize the selective separation and recovery of nickel, manganese and cobalt in the water immersion residue;

[0045] S6, the magnetic separation concentrate is subjected to acid leaching, and a metal leaching solution is obtained by filtration, and then an oxidizing agent and an alkaline substance are added to the metal leaching solution for impurity removal, the final pH value of the solution is maintained at 4.5-5.5, and a solution after impurity removal is obtained by filtration; this step can realize the selective separation and recovery of nickel, manganese and cobalt in the magnetic separation concentrate and impurity removal;

[0046] S7, the proportion of nickel, cobalt and manganese in the impurity-removed solution is adjusted to reach the proportion of nickel, cobalt and manganese in the target ternary positive electrode material, and then ammonia solution and sodium hydroxide solution are added to carry out a coprecipitation reaction, and finally a ternary positive electrode material precursor is prepared through filtering, washing and drying.

[0047] The present application selectively recovers high value-added metals such as nickel, manganese and cobalt in water leaching residue by adopting a wet low-intensity magnetic separation-acid leaching process; after simple impurity removal, a nickel-cobalt-manganese ternary positive electrode material precursor is obtained by using a coprecipitation method.

[0048] In the present embodiment, during the ball milling and pulping process, zirconium oxide is used for ball milling and pulping treatment to bring in as little iron impurities as possible and reduce the difficulty of subsequent impurity removal; the liquid-solid ratio is 0.5-2 mL / g, and further 1 mL / g; during the magnetic separation process, the particle size range of the pulping liquid is 60%-90% of-0.074 mm, and the magnetic field strength of the magnetic separation is 2000-3500 Oe.

[0049] The present application does not limit the type of acid selected in the acid leaching step, and the person skilled in the art can select according to the actual situation. In some specific embodiments of the present application, the acid selected is sulfuric acid with a concentration of 1-3 mol / L, the liquid-solid ratio is 5-10 mL / g, the leaching temperature is 30-50℃, and the leaching time is 0.5-2 h.

[0050] In the present embodiment, the oxidizing agent is a hydrogen peroxide solution with a mass fraction of 20-30%; the volume ratio of the hydrogen peroxide solution to the metal leaching solution is 1-5 mL / L.

[0051] The present application does not limit the type of alkaline substance, and the person skilled in the art can select according to the actual situation. For example, it can be sodium hydroxide, potassium hydroxide, sodium carbonate, etc.

[0052] In the present embodiment, the proportion of nickel, cobalt and manganese in the impurity-removed solution is adjusted by dissolving nickel salt, cobalt salt or manganese salt into the impurity-removed solution.

[0053] The present application does not limit the proportion of nickel, cobalt and manganese in the target ternary positive electrode material, and the person skilled in the art can select according to the actual situation, for example, it can be 1:1:1, 5:2:3 or 6:2:2, etc.

[0054] In the present embodiment, in the coprecipitation reaction, the concentration of the ammonia water used when dropping is 0.5-1 mol / L, the concentration of the sodium hydroxide solution is 3-5 mol / L, the concentration of the ammonia water as the bottom liquid is 0.5-1 mol / L, and the volume ratio of the ammonia water bottom liquid to the impurity-removed solution after adjusting the proportion of nickel, cobalt and manganese is (0.1-1):1.

[0055] In this embodiment, the reaction conditions of the co-precipitation reaction are: pH 10-12, stirring speed 500-800 rpm / min, temperature 45-65 ℃, and aging time 12-24 h.

[0056] Pre-experiment

[0057] By investigating the effect of different ultrasonic times on the ultrasonic-assisted water leaching of lithium, a suitable ultrasonic time range was selected. The specific conditions are as follows: the roasting temperature is kept at 650 ℃, the roasting time is 60 min, the roasting atmosphere is nitrogen, the ultrasonic power is 450 W, the ultrasonic time is 2-30 min, and the ultrasonic-assisted water leaching conditions are liquid-solid ratio 10 mL / g and leaching temperature 25 ℃. The results are shown in Figure 4

[0058] By Figure 4 It can be seen that with the continuous extension of the ultrasonic treatment time, the Li leaching rate presents a change rule of first increasing and then reaching equilibrium; when the ultrasonic time is 20 min, the leaching rate reaches the highest value of 93.50%.

[0059] Example 1

[0060] A method for recovering lithium from waste lithium ion batteries and regenerating ternary precursors, comprising the following steps:

[0061] (1) The waste ternary lithium battery is subjected to industrial inert pulverization-classification process under nitrogen atmosphere to obtain positive and negative mixed electrode materials, and the particle size of the materials is 90% of -0.5 mm.

[0062] (2) 10 g of the positive and negative mixed electrode material powder is loaded into a crucible and placed in a muffle furnace, and the temperature is raised to a roasting temperature of 650 ℃ at a heating rate of 10 ℃ / min, the holding time is 1.5 h, the roasting atmosphere is nitrogen, and the temperature is naturally cooled to room temperature.

[0063] (3) The roasted mixed electrode material is added to deionized water, and the liquid-solid ratio is 15 mL:1 g. After mixing, it is transferred to an ultrasonic reactor and subjected to ultrasonic-assisted water leaching under the conditions of ultrasonic power 400 W, temperature 25 ℃, and ultrasonic time 25 min. The lithium-containing filtrate and water leaching residue are obtained by filtration.

[0064] (4) The lithium-containing filtrate is evaporated and concentrated to a lithium content of 25 g / L, and then saturated Na2CO3 solution is added. The amount of sodium carbonate added is 1.3 times the theoretical amount. After stirring for a period of time until no new precipitate is generated, the crude lithium carbonate is obtained by filtration.

[0065] ​(5) The recovered crude lithium carbonate is washed with 90 ℃ deionized water for 3 times, and refined lithium carbonate is obtained after drying, with a purity of 99.0%, and a final lithium recovery rate of 92.2%.

[0066] (6) The water-immersed residue is subjected to zirconium oxide ball milling to obtain a slurry, with a liquid-solid ratio of 1 mL / g during the ball milling process, and the particle size of the slurry ranges from -0.074 mm to 80%. The slurry is subjected to magnetic separation under a magnetic field strength of 2500 Oe to obtain a magnetic separation concentrate and a magnetic separation tailing. The grades of nickel, cobalt, manganese, aluminum and copper in the magnetic separation concentrate are 20.65%, 10.82%, 23.16%, 0.18% and 0.16% respectively, and the recovery rates of nickel, cobalt, manganese, aluminum and copper are 98.20%, 98.74%, 95.96%, 1.14% and 0.60% respectively.

[0067] (7) The magnetic separation concentrate is leached under the conditions of a sulfuric acid concentration of 2 mol / L, a liquid-solid ratio of 10 mL / g, a leaching temperature of 50 ℃ and a leaching time of 1 h. The leaching rates of valuable metals nickel, cobalt and manganese in the leaching solution are 99.21%, 99.74% and 99.25% respectively, and the concentrations of nickel, cobalt, manganese, aluminum, copper and iron in the leaching solution are 10.24 g / L, 5.39 g / L, 11.49 g / L, 0.089 g / L, 0.041 g / L and 0.085 g / L respectively.

[0068] (8) A hydrogen peroxide solution with a mass fraction of 27.5% is added to the acid leaching solution containing nickel, cobalt and manganese, with a volume ratio of 2 mL / L; then sodium hydroxide is used to adjust the final pH value of the solution to 5.0, and then the solution is subjected to solid-liquid separation to obtain a filtrate; the concentrations of nickel, cobalt, manganese, aluminum, copper and iron in the filtrate are 10.18 g / L, 5.36 g / L, 11.42 g / L, 0.005 g / L, 0.010 g / L and 0.004 g / L respectively.

[0069] (9) Nickel salt, cobalt salt or manganese salt is dissolved in the filtrate according to the required molar ratio of nickel, cobalt and manganese in the NCM111 type positive electrode material, and the molar ratio of nickel, cobalt and manganese in the leaching solution is controlled to be 1:1:1, and the total molar concentration of nickel, cobalt and manganese metal ions is 2 mol / L.

[0070] (10) A peristaltic pump is used to drop 4 mol / L sodium hydroxide solution, 0.5 mol / L ammonia solution and the leaching solution after adjusting the concentration into 0.5 mol / L ammonia bottom solution for co-precipitation reaction. During the dropping process, the pH value of the reaction system is maintained at 11.6, the stirring speed is controlled at 800 rpm / min, the stirring temperature is 60 ℃, and the stirring time is 18 h, to obtain a co-precipitation reaction product. The volume ratio of the ammonia bottom solution to the impurity-removed solution after adjusting the nickel, cobalt and manganese ratio is 0.5:1.

[0071] (11) The precipitate is washed multiple times with pure water, then placed in a vacuum drying oven at 95°C. After drying, the sample is ground and packaged to obtain the 111-type ternary precursor.

[0072] Example 2

[0073] A method for recovering lithium and regenerating ternary precursors from waste lithium-ion batteries, comprising the following steps:

[0074] (1) The waste ternary lithium battery is crushed and classified under a nitrogen atmosphere to obtain a positive and negative electrode mixed material, and the particle size of the material is 90% -0.2 mm.

[0075] (2) 10 g of the positive and negative electrode mixed material powder is placed in a crucible and placed in a muffle furnace. The temperature is raised to 650°C at a rate of 10°C / min, and the holding time is 1 h. The roasting atmosphere is nitrogen, and the temperature is naturally cooled to room temperature.

[0076] (3) The roasted mixed electrode material is added to deionized water with a liquid-to-solid ratio of 20 mL:1 g. After mixing, it is transferred to an ultrasonic reactor and subjected to ultrasonic-assisted water immersion under the following conditions: ultrasonic power 450 W, temperature 25°C, and ultrasonic time 20 min. The filtrate containing lithium and water leaching residue are obtained by filtration.

[0077] (4) The lithium-containing filtrate is evaporated and concentrated to a lithium content of 30 g / L, then saturated Na2CO3 solution is added. The amount of sodium carbonate added is 1.5 times the theoretical amount. After stirring for a period of time until no new precipitate is formed, the crude lithium carbonate is obtained by filtration.

[0078] (5) The recovered crude lithium carbonate is washed with 90°C deionized water for 3 times, and refined lithium carbonate is obtained after drying. The purity of lithium carbonate is 97.8%, and the final lithium recovery rate is 95.6%.

[0079] (6) The water leaching residue is subjected to zirconia ball milling to obtain a slurry. The liquid-to-solid ratio during ball milling is 1 mL / g, and the particle size of the slurry is 90% -0.074 mm. The slurry is subjected to magnetic separation under a magnetic field strength of 3000 Oe to obtain a magnetic separation concentrate and a magnetic separation tailings. The grades of nickel, cobalt, manganese, aluminum, and copper in the magnetic separation concentrate are 26.09%, 14.23%, 29.17%, 0.29%, and 0.31%, respectively. The recoveries of nickel, cobalt, manganese, aluminum, and copper are 93.25%, 95.57%, 92.83%, 2.10%, and 1.44%, respectively.

[0080] (7) The magnetic separation concentrate was leached under the conditions of sulfuric acid concentration of 2.5 mol / L, liquid-solid ratio of 10 mL / g, leaching temperature of 50 ℃, and leaching time of 1 h, and the leaching rates of valuable metals nickel, cobalt and manganese in the leaching solution were 99.31%, 99.56% and 99.18% respectively, and the concentrations of nickel, cobalt, manganese, aluminum, copper and iron in the leaching solution were 12.95 g / L, 7.08 g / L, 14.46 g / L, 0.143 g / L, 0.080 g / L and 0.127 g / L respectively.

[0081] (8) The mass fraction of hydrogen peroxide solution added to the acid leaching solution containing nickel, cobalt and manganese was 27.5%, and the volume ratio was 2 mL / L; then sodium hydroxide was used to adjust the final pH value of the solution to 4.9, and then the filtrate was obtained by solid-liquid separation; the concentrations of nickel, cobalt, manganese, aluminum, copper and iron in the filtrate were 12.88 g / L, 7.04 g / L, 14.37 g / L, 0.007 g / L, 0.010 g / L and 0.006 g / L respectively.

[0082] (9) The nickel salt, cobalt salt or manganese salt was dissolved in the leaching solution according to the required molar ratio of nickel, cobalt and manganese in the NCM523 type positive electrode material, and the molar ratio of nickel, cobalt and manganese in the leaching solution was supplemented to 5:2:3, and the total molar concentration of nickel, cobalt and manganese metal ions was 2 mol / L.

[0083] (10) The 4 mol / L sodium hydroxide solution, 0.5 mol / L ammonia solution and the leaching solution after adjusting the concentration were dropped into the 0.5 mol / L ammonia bottom solution for co-precipitation reaction using a peristaltic pump, the pH of the reaction system was maintained at 11.6 during the dropping process, the stirring speed was controlled at 800 rpm / min, the stirring temperature was 60 ℃, and the stirring time was 24 h, and the co-precipitation reaction product was obtained. The volume ratio of the ammonia bottom solution to the impurity-removed solution after adjusting the nickel, cobalt and manganese ratio was 0.5:1.

[0084] (11) The precipitate was washed several times using pure water, and then was placed in a vacuum drying oven at 95 ℃ for drying, and after drying, the sample was ground and bagged to obtain the 523 type ternary precursor.

[0085] By Figure 4 It can be seen that the XRD spectrum of the refined lithium carbonate prepared in Example 2 is completely consistent with the standard spectrum peak (JCPDS No. 22-1441), and has good crystallinity and particle morphology.

[0086] By Figure 5 It can be seen that the Ni 0.5 Co 0.2 Mn 0.3The main characteristic diffraction peaks of the (OH)2precursor are at 2θ = 19.26, 33.06, 38.54, 52.10, 59.05, 60.24 and 62.73, which are consistent with the standard card JCPDS 14-0117, and the hexagonal layered structure is formed, and no diffraction peaks of other basic oxides are observed, which indicates that cobalt and manganese replace part of nickel during the co-precipitation process to form a ternary precursor.

[0087] By Figure 6 It can be seen that the nickel-cobalt-manganese ternary precursor formed in Example 2 has a smooth particle surface, high sphericity and good particle dispersion.

[0088] Comparative Example 1

[0089] Except that ordinary magnetic stirring leaching is used instead of ultrasonic-assisted water leaching in step (3), and the rotation speed is set to 400 rpm and the leaching time is set to 2 h, the rest is consistent with Example 1.

[0090] The method is used to recover lithium from the positive and negative electrode mixed materials of the waste ternary lithium battery, and the results show that after 10 g of the positive and negative electrode mixed electrode material powder is treated, the lithium recovery rate is 77.9%, and the purity of the obtained lithium carbonate is 98.5%. The reason may be that under the conventional water leaching conditions, the lithium deposited on the negative electrode sheet cannot be effectively recovered, and at the same time, the adsorption of lithium ions by the residual negative electrode material graphite in the calcination product cannot be reduced, thereby significantly reducing the lithium recovery rate obtained by the conventional water leaching process.

[0091] Comparative Example 2

[0092] Except that the calcination temperature in step (2) is set to 750 ℃, the rest is consistent with Example 1.

[0093] The method is used to recover lithium from the positive and negative electrode mixed materials of the waste ternary lithium battery, and the results show that after 10 g of the positive and negative electrode mixed electrode material powder is treated, the lithium recovery rate is 77.9%, and the purity of the obtained lithium carbonate is 98.5%. The reason may be that under the conventional water leaching conditions, the lithium deposited on the negative electrode sheet cannot be effectively recovered, and at the same time, the adsorption of lithium ions by the residual negative electrode material graphite in the calcination product cannot be reduced, thereby significantly reducing the lithium recovery rate obtained by the conventional water leaching process.

[0094] Comparative Example 3

[0095] Except that the ultrasonic power in step (3) is set to 200 W, the rest is consistent with Example 1.

[0096] The method is used for recovering lithium from the positive and negative mixed materials of the waste ternary lithium battery, and it is shown that the recovery rate of lithium is 93.8% and the purity of the obtained lithium carbonate is 95.7% after 10 g of the positive and negative mixed electrode material powder is treated by the above method. It can be seen from the example that the recovery rate of lithium is slightly increased under the condition of water immersion assisted by too high ultrasonic power, but the purity of the lithium carbonate is obviously reduced, because the ultrasonic power is too high, which promotes the dissolution of lithium fluoride in the calcined product, thereby reducing the purity of the lithium carbonate.

[0097] Example 4

[0098] Except that the ultrasonic power is set to 500 W in step (3), the rest is consistent with example 1.

[0099] The method is used for recovering lithium from the positive and negative mixed materials of the waste ternary lithium battery, and it is shown that the recovery rate of lithium is 93.8% and the purity of the obtained lithium carbonate is 95.7% after 10 g of the positive and negative mixed electrode material powder is treated by the above method. It can be seen from the example that the recovery rate of lithium is slightly increased under the condition of water immersion assisted by too high ultrasonic power, but the purity of the lithium carbonate is obviously reduced, because the ultrasonic power is too high, which promotes the dissolution of lithium fluoride in the calcined product, thereby reducing the purity of the lithium carbonate.

[0100] Compared with the prior art, the beneficial effects of the present application also include:

[0101] (1) The present application breaks through the established thinking of the traditional process "sorting first and then processing", adopts the method of low-temperature in-situ self-reduction roasting and ultrasonic-assisted water immersion, realizes the effective separation and efficient extraction of metal lithium and nickel-cobalt-manganese metal in the waste lithium ion battery positive and negative mixed materials which can be pre-selected, and the metal lithium is transferred to the solution in advance.

[0102] (2) The method of ultrasonic-assisted water immersion adopted by the present application has the advantages of short leaching time and high lithium leaching rate compared with the traditional conventional water immersion method, solves the problem of low metal lithium yield and purity in the industry at present, and the recovery rate of metal lithium in the whole treatment process is increased from about 80% in the industry to more than 92%. Continuous and stable large-scale industrial production can be realized.

[0103] (3) In the present application, nickel, cobalt and manganese are efficiently and selectively separated and recovered from the water immersion residue by ball milling and slurry-magnetic separation, the impurity content in the magnetic separation concentrate is low, high-purity nickel, cobalt and manganese-containing leaching solution can be obtained by simple acid leaching, the consumption of reagents required for impurity removal is reduced, the production cost is reduced, and the wet leaching solution is used to regenerate nickel-cobalt-manganese ternary precursor, avoiding the separation steps such as extraction and precipitation after leaching, which maximizes the comprehensive recovery efficiency of the metal and realizes the closed circuit of the recovery process and the resource regeneration of the positive electrode material.

[0104] The above description of the specific embodiments of the present application is not intended to limit the scope of the present application. Any other corresponding changes and modifications made according to the technical concept of the present application should be included in the scope of protection of the claims of the present application.

Claims

1. A method for recovering lithium from a spent lithium-ion battery, characterized by, The method comprises the following steps: The waste lithium ion battery is crushed and classified by an industrial inert process to obtain positive and negative mixed electrode materials; The positive and negative mixed electrode materials are subjected to in-situ self-reduction roasting to obtain roasted products; The roasted products are mixed with deionized water to form a slurry, and then the slurry is placed in an ultrasonic reactor for ultrasonic-assisted water leaching, and then filtered to obtain a lithium-containing filtrate and a water leaching residue; wherein In the in-situ self-reduction roasting process, the roasting temperature is 600-700 DEG C, and the roasting time is 1-2 h; In the ultrasonic-assisted water leaching process, the liquid-solid ratio of the slurry is 15-20 mL / g, the power of the ultrasonic wave is 400-450 W, the leaching temperature is 20-35 DEG C, and the leaching time is 20-25 min.

2. The method for recovering lithium from a waste lithium ion battery according to claim 1, characterized by, In the industrial inert crushing and classification process, the inert gas selected is nitrogen or carbon dioxide; the particle size of the positive and negative mixed electrode materials is less than 1 mm.

3. The method of claim 1, wherein the lithium is recovered from the spent lithium-ion battery by the steps of: In the in-situ self-reduction roasting process, the roasting atmosphere is nitrogen or carbon dioxide. ​ 4. The method of claim 1, wherein the lithium is recovered from the spent lithium-ion battery by, The method further comprises the following steps: After the lithium-containing filtrate is evaporated and concentrated, a theoretical amount of 1.0-1.5 times of a carbonate precipitant is added, and then filtered to obtain crude lithium carbonate, and then the crude lithium carbonate is washed with water, and dried to obtain refined lithium carbonate; wherein The lithium content in the evaporated and concentrated lithium-containing filtrate is 20-30 g / L; The carbonate precipitant is at least one of saturated potassium carbonate solution or saturated sodium carbonate solution.

5. A method for preparing ternary precursors from spent lithium-ion batteries, characterized in that, The method comprises the following steps: The water leaching residue in the method for recovering lithium from waste lithium ion batteries according to any one of claims 1-4 is subjected to ball milling and slurry treatment to obtain a slurry liquid, and then the slurry liquid is subjected to magnetic separation to obtain a magnetic separation concentrate and a magnetic separation tailing; The magnetic separation concentrate is subjected to acid leaching, and then filtered to obtain a metal leaching solution, and then an oxidizing agent and an alkaline substance are added to the metal leaching solution for impurity removal, the final pH value of the solution is maintained at 4.5-5.5, and then filtered to obtain a solution after impurity removal; The ratio of nickel, cobalt and manganese in the solution after impurity removal is adjusted to reach the ratio of nickel, cobalt and manganese in a target ternary positive electrode material, and then an ammonia solution and a sodium hydroxide solution are added for co-precipitation reaction, and finally filtered, washed and dried to prepare a ternary positive electrode material precursor.

6. The method for preparing ternary precursors from waste lithium-ion batteries according to claim 5, characterized in that, In the ball milling and slurry process, zirconia balls are used for milling and slurry treatment, and the liquid-solid ratio is 0.5-2 mL / g; in the magnetic separation process, the particle size of the slurry liquid ranges from-0.074 mm to 60%-90%, and the magnetic field strength is 2000-3500 Oe.

7. The method for preparing ternary precursors from waste lithium-ion batteries according to claim 5, characterized in that, In the acid leaching process, the acid concentration is 1-3 mol / L of sulfuric acid, the liquid-solid ratio is 5-10 mL / g, the leaching temperature is 30-50 DEG C, and the leaching time is 0.5-2 h.

8. The method for preparing ternary precursors from waste lithium-ion batteries according to claim 5, characterized in that, In the impurity removal process, the oxidizing agent is a hydrogen peroxide solution with a mass fraction of 20-30%, and the volume ratio of the hydrogen peroxide solution to the metal leaching solution is 1-5 mL / L.

9. The method for preparing ternary precursors from waste lithium-ion batteries according to claim 5, characterized in that, In the process of the co-precipitation reaction, the concentration of ammonia used in the dropping process is 0.5-1 mol / L, the concentration of sodium hydroxide solution is 3-5 mol / L, the concentration of ammonia used as the bottom solution is 0.5-1 mol / L, and the volume ratio of the ammonia bottom solution to the impurity-removed solution after adjusting the proportions of nickel, cobalt and manganese is (0.1-1):1; the reaction conditions of the co-precipitation reaction are as follows: pH 10-12, stirring speed 500-800 rpm / min, temperature 45-65 ℃, and aging time 12-24 h.

Images