Method and system for recycling waste lithium battery electrode materials

Abstract

The invention provides a method and system for recycling electrode materials of waste lithium batteries. The method comprises the following steps: pre-treating waste lithium batteries to obtain electrode materials of the waste lithium batteries; pre-pyrolyzing the electrode materials to generate solid products and volatile gases; re-selecting the solid products to separate aluminum foil and copper foil to obtain solid residues after the aluminum foil and copper foil are separated; gasifying the solid residues and volatile gases simultaneously by using water vapor introduced from the outside, so that the volatile gases and water vapor react with the solid residues to obtain recyclable solids and combustible gases, and to fix fluorine in the electrode materials. In the process of recycling waste lithium batteries, the invention saves heating energy consumption, reduces the volatilization of valuable metals and the discharge of fluorine-containing wastewater in the recycling process, and effectively realizes the resource-based and harmless utilization of waste lithium batteries.

Description

Technical Field

[0001] The invention belongs to the technical field of recycling waste lithium batteries, and in particular relates to a method and system for recycling electrode materials of waste lithium batteries. Background Art

[0002] Lithium batteries have the advantages of high voltage, small size, high specific energy, low self-discharge and high safety. They are widely used in various fields. However, with the widespread use of lithium batteries, the number of waste lithium batteries is also increasing. Waste lithium batteries not only contain a large amount of valuable metals such as cobalt and lithium, but also contain toxic and harmful components such as organic electrolytes and organic binders. Efficient recycling of them can not only avoid waste of resources, but also reduce their pollution and harm to the environment.

[0003] Due to the high recovery rate of valuable components, hydrometallurgical process has become the main recycling method for waste lithium batteries. However, considering the high cost and pollution, hydrometallurgy is only used to recover highly economical metals from cathode materials (such as Co, Ni, Mn and Li). At present, there are many technologies for recycling waste lithium batteries, such as (1) waste lithium ion battery pyrolysis method and system (CN109888370A) which achieves harmless treatment of electrolyte while obtaining electrode materials through cooling, shelling, pyrolysis (500-650°C) and physical adsorption / alkali absorption processes to achieve recycling of waste lithium batteries; (2) waste lithium battery pyrolysis recovery system and treatment method (CN10953926A) which uses small molecule pyrolysis gas and large molecule pyrolysis oil obtained by pyrolysis as fuel to burn for pyrolysis energy, thereby achieving The pyrolysis system is highly efficient and energy-saving, and the tail gas treatment mechanism is used to harmlessly treat the tail gas to achieve the recycling of waste lithium batteries; (3) A method for pyrolysis and defluorination of waste lithium batteries (CN111495925A) is to dismantle and crush the waste lithium batteries after discharge, dry and sort the crushed products, and then pyrolyze the sorted products (200-1000°C) to absorb fluorine and chlorine in situ; the pyrolysis products are then dispersed and screened to obtain black powder, and conventional wet or fire defluorination processes are used to further reduce the fluorine content in the black powder and improve the efficiency of defluorination, so as to achieve the recycling of waste lithium batteries; the above patented technologies are all based on the use of pyrolysis technology to efficiently decompose organic matter such as electrolyte, binder, plastic diaphragm, etc., focusing on energy saving in the pyrolysis process and harmlessness of pyrolysis products, but have not yet solved the following problems:

[0004] (1) Avoidance of volatilization of valuable metals during the pyrolysis process; when the pyrolysis temperature is higher than 750°C, the Li2CO3 produced during the pyrolysis process will volatilize and cause mass loss, making the Li recovery rate less than 80%;

[0005] (2) The influence of the existence form of valuable metals in the solid residue on the recovery effect; for example, a lower pyrolysis temperature (<600°C) does not cause significant chemical changes in the valuable metals in the cathode material, and the valuable metals are still recovered in a higher valence state (such as Co 3 + ) will affect the subsequent leaching effect and cost;

[0006] (3) The solid residue obtained by pyrolysis often contains a lot of carbon, which also increases the burden of subsequent flotation separation;

[0007] (4) In terms of flue gas purification, the removal of acidic gases (such as HF) in flue gas is often done by spraying alkaline solution, which will also increase the subsequent treatment burden of fluorine-containing wastewater.

[0008] In view of the defects of the existing waste lithium battery recycling process such as volatilization of valuable metals, difficulty in leaching high-priced metals, high carbon content in pyrolysis solid residues, and heavy burden of fluorine-containing wastewater treatment, the present invention proposes a waste lithium battery pyrolysis method and system with high treatment efficiency and low operating energy consumption, so as to restore high-priced metals, reduce the volatilization of valuable metals and the discharge of fluorine-containing wastewater, reduce the carbon content in the solid residues, and realize the resource and harmless utilization of waste lithium batteries. Summary of the invention

[0009] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a method and system for recycling waste lithium battery electrode materials, which is used to solve the problem of volatilization of valuable metals in the prior art waste lithium battery recycling process, resulting in a reduced recovery rate.

[0010] To achieve the above-mentioned purpose and other related purposes, the present invention provides a method for recycling electrode materials of waste lithium batteries, comprising the following steps: pre-treating waste lithium batteries to obtain electrode materials of the waste lithium batteries; pre-pyrolyzing the electrode materials to generate solid products and volatile gases; re-selecting the solid products to separate aluminum foil and copper foil and recycling them to obtain solid residues after separating the aluminum foil and the copper foil; and simultaneously gasifying the solid residues, the volatile gases and water vapor introduced from the outside, so that the volatile gases and the water vapor react with the solid residues to obtain recyclable solids and combustible gases, and to fix the fluorine in the electrode materials.

[0011] In one embodiment of the present invention, the working temperature corresponding to the pre-pyrolysis is 350-550°C, and the working time is 20-30 minutes; the combustible gas is used to provide heat for the pre-pyrolysis; the working temperature corresponding to the gasification is 600-750°C; and the reaction time of the volatile gas and the water vapor with the solid residue is 30-50 minutes.

[0012] In one embodiment of the present invention, a bouncing screen is used to reselect the solid product to separate the aluminum foil and the copper foil from the solid product for recovery; the solid residue includes any one or a combination of the following: carbon, cobalt oxide, manganese oxide, nickel oxide, lithium cobalt oxide and nickel; the components of the recyclable solid include any one or a combination of the following: lithium carbonate, manganese oxide, carbon, lithium fluoride, cobalt, nickel oxide, cobalt oxide; wherein the weight fraction of the carbon is less than 10%.

[0013] The present invention provides a recycling system for waste lithium battery electrode materials, comprising: a pre-pyrolysis furnace, a gravity separation device, a gasification furnace, a cooling and discharging mechanism and an absorption device; the discharging port on the pre-pyrolysis furnace is connected to the gravity separation device, and the volatile gas outlet on the pre-pyrolysis furnace is connected to the gasification furnace, and is used for pre-pyrolysis of the electrode materials of the waste lithium battery to generate solid products and volatile gases; the gravity separation device is used for gravity separation of the solid products to separate aluminum foil and copper foil from the solid products and recycle them, and obtain the solid residue after the aluminum foil and the copper foil are separated; the gasification furnace The feed inlet is connected to the gravity selection device, and the gasifier is provided with a water vapor inlet, which is used to introduce water vapor into the gasifier. The gasifier is used to gasify the solid residue, the volatile gas and the water vapor at the same time, so that the volatile gas and the water vapor react with the solid residue to obtain recyclable solid and combustible gas, and to fix the fluorine in the electrode material; the cooling and discharging mechanism is connected to the gasifier, and is used to recover the recyclable solid; the absorption device is connected to the combustible gas outlet on the gasifier, and is used to recover the combustible gas.

[0014] In one embodiment of the present invention, it also includes: a first combustion chamber and a second combustion chamber; wherein the first combustion chamber is respectively connected to the pre-pyrolysis furnace and the absorption device, and is used to burn the combustible gas to provide heat for the pre-pyrolysis furnace; the second combustion chamber is connected to the gasification furnace, and is provided with clean fuel therein, which is used to provide heat for the gasification furnace.

[0015] In one embodiment of the present invention, it also includes: a dust removal device and a flue gas purification system; wherein the dust removal device is arranged between the absorption device and the first combustion chamber, and is used to remove dust from the combustible gas; the dust removal device adopts a cyclone dust collector or an electrostatic dust collector; the flue gas purification system is connected to the flue gas outlet of the pre-pyrolysis furnace, and is used to purify the flue gas discharged from the flue gas outlet.

[0016] In one embodiment of the present invention, it further includes: a purification device; the purification device is arranged between the dust removal device and the first combustion chamber, and is used to purify the combustible gas after the dust removal treatment by the dust removal device.

[0017] In one embodiment of the present invention, the flue gas outlet of the pre-pyrolysis furnace is connected to the water vapor inlet for providing the water vapor to the gasification furnace.

[0018] In one embodiment of the present invention, it also includes: a water leaching device with CO2 passing through it; the water leaching device is connected to the cooling and discharging mechanism, and is used to perform water leaching treatment on the recyclable solid under the condition of CO2 passing through it, so as to separate the soluble lithium salt and insoluble substances in the recyclable solid.

[0019] In one embodiment of the present invention, the absorption device is equipped with any one or a combination of the following chemical absorbents: lime (CaO), slaked lime (Ca(OH)2), modified Ca(OH)2, dolomite calcined product, sodium carbonate, and caustic soda.

[0020] As described above, the method and system for recycling waste lithium battery electrode materials of the present invention have the following beneficial effects:

[0021] (1) Compared with the prior art, the present invention utilizes the gas produced by the gasifier for heating during the recycling process of waste lithium batteries, thereby saving heating energy consumption; utilizes low-temperature pre-pyrolysis and a gasifier to reduce the volatilization of valuable metals during the recycling process; and utilizes the special atmosphere and absorption device in the gasifier to reduce the discharge of fluorine-containing wastewater, thereby effectively realizing the resource-based and harmless utilization of waste lithium batteries.

[0022] (2) Due to the elimination of the binder, the positive electrode active material of the waste lithium battery can be completely separated from the aluminum foil. The high-valent metal Co in the positive electrode material of the waste lithium battery can be completely separated from the aluminum foil by utilizing the synergistic effect of pyrolytic carbon, HF, additive carbon black and graphite in the reduction process in the gasifier. 3+ Reduction to a low-valent state makes the subsequent hydrometallurgical treatment process convenient and simple.

[0023] (3) The present invention can reuse the pyrolysis products of the organic binder after combustion, thereby reducing operating energy consumption.

[0024] (4) The reduction process of the present invention can make fluorine react with LiCoO2 and be fixed in lithium fluoride with utilization value, so as to realize the recovery and utilization of fluorine, and through the dry absorption of the remaining hydrogen fluoride in the gas product, the amount of fluorine-containing wastewater generated by the subsequent flue gas purification system can be effectively reduced; at the same time, gasification can effectively reduce the carbon content in the solid residue, reducing the separation burden in the subsequent hydrometallurgical process. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A flow chart showing a method for recycling waste lithium battery electrode materials according to an embodiment of the present invention is shown.

[0026] Figure 2 Shown is a working principle diagram of a waste lithium battery electrode material recycling system in one embodiment of the present invention.

[0027] Figure 3 Shown is a working principle diagram of another embodiment of the waste lithium battery electrode material recycling system of the present invention.

[0028] Description of symbols

[0029] 1 Pre-pyrolysis furnace

[0030] 2 Reselection device

[0031] 3 Gasifier

[0032] 4 Cooling discharging mechanism

[0033] 5 Absorption device

[0034] 6 Feeding mechanism

[0035] 7 First combustion chamber

[0036] 8 Second combustion chamber

[0037] 9 Dust removal device

[0038] 10 Flue gas purification system

[0039] 11. Purification device

[0040] 12 water leaching device DETAILED DESCRIPTION

[0041] The following describes the embodiments of the present invention through specific embodiments, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0042] It should be noted that the illustrations provided in the following embodiments are only used to illustrate the basic concept of the present invention in a schematic manner, and thus the illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0043] Compared with the prior art, the present invention provides a method and system for recycling electrode materials of waste lithium batteries. In the process of recycling waste lithium batteries, the present invention utilizes the gas produced by the gasifier for heating, thereby saving heating energy consumption; utilizes low-temperature pre-pyrolysis and a gasifier to reduce the volatilization of valuable metals in the recycling process; utilizes a special atmosphere and an absorption device in the gasifier to reduce the discharge of fluorine-containing wastewater, thereby effectively realizing the resource and harmless utilization of waste lithium batteries; the positive electrode active material of the waste lithium battery can be completely detached and separated from the aluminum foil due to the elimination of the binder; and utilizes the synergistic effect of pyrolytic carbon, HF, additive carbon black and graphite in the reduction process in the gasifier to realize the high-valent metal Co in the positive electrode material of the waste lithium battery. 3+ Reduction to a low-valent state makes the subsequent hydrometallurgical treatment process convenient and simple; the present invention can reuse the pyrolysis products of the organic binder after combustion, thereby reducing operating energy consumption; the reduction process of the present invention can make fluorine react with LiCoO2 and be fixed in lithium fluoride with utilization value, thereby realizing fluorine recovery and utilization, and by dry absorption of the remaining hydrogen fluoride in the gas product, the amount of fluorine-containing wastewater generated by the subsequent flue gas purification system can be effectively reduced; at the same time, gasification can effectively reduce the carbon content in the solid residue, thereby reducing the separation burden in the subsequent hydrometallurgical process.

[0044] like Figure 1 As shown, in one embodiment, the method for recycling waste lithium battery electrode materials of the present invention comprises the following steps:

[0045] Step S1, pre-treating the waste lithium batteries to obtain electrode materials of the waste lithium batteries.

[0046] It should be noted that the waste lithium battery is pretreated by an existing pretreatment method in the field to obtain its electrode material. The specific working principle is not a condition limiting the present invention, so it will not be described in detail here.

[0047] Step S2: pre-pyrolyze the electrode material to generate solid products and volatile gases.

[0048] In one embodiment, the working temperature corresponding to the pre-pyrolysis is 350-550° C., so that a good peeling effect is achieved between the current collector and the electrode material after pyrolysis, and the aluminum foil is prevented from being oxidized and becoming brittle, which affects the re-selection operation in the subsequent step S2; the working time is 20-30 minutes.

[0049] Step S3, separating the aluminum foil and the copper foil from the solid product by gravity selection and recovering them to obtain a solid residue after separating the aluminum foil and the copper foil.

[0050] It should be noted that the solid product is not limited to aluminum foil and copper foil, and other bulk substances can also be separated.

[0051] In one embodiment, a spring screen is used to reselect the solid product, so as to separate the aluminum foil and the copper foil from the solid product and recycle them.

[0052] In one embodiment, the solid residue includes but is not limited to any one or a combination of the following: carbon (C), cobalt oxide (CoO), manganese oxide (MnO), nickel oxide (NiO), lithium cobalt oxide (LiCoO2) and nickel (Ni).

[0053] Step S4, gasifying the solid residue, the volatile gas and the water vapor introduced from the outside at the same time, so that the volatile gas and the water vapor react with the solid residue to obtain recyclable solid and combustible gas, and to fix the fluorine in the electrode material.

[0054] In one embodiment, the working temperature corresponding to the gasification is 600-750° C., which ensures the carbon thermal reduction temperature and avoids obvious volatilization of lithium carbonate; the reaction time of the volatile gas and the water vapor reacting with the solid residue is 30-50 minutes.

[0055] In one embodiment, step S4 can achieve fixation of more than 50% of fluorine in the electrode material.

[0056] In one embodiment, the components of the recyclable solid include but are not limited to any one or a combination of the following: lithium carbonate (Li2CO3), manganese oxide (MnO), carbon (C), lithium fluoride (LiF), cobalt (Co), nickel oxide (NiO), and cobalt oxide (CoO); wherein the weight fraction of the carbon is less than 10%; the valuable metals (such as lithium Li and cobalt Co) in the recyclable solid are all present in a low-valent state.

[0057] In one embodiment, the combustible gas obtained in step S4 can be used to provide heat for the pre-pyrolysis in step S2.

[0058] It should be noted that the protection scope of the method for recycling waste lithium battery electrode materials described in the present invention is not limited to the execution order of the steps listed in this embodiment. All solutions achieved by adding, reducing or replacing steps in the prior art based on the principles of the present invention are included in the protection scope of the present invention.

[0059] like Figure 2 and Figure 3 As shown, in one embodiment, the recycling system of waste lithium battery electrode materials of the present invention includes a pre-pyrolysis furnace 1, a gravity separation device 2, a gasification furnace 3, a cooling and discharging mechanism 4 and an absorption device 5.

[0060] Specifically, the discharge port at the lower part of the pre-pyrolysis furnace 1 is connected to the gravity separation device 2, and the volatile gas outlet on the pre-pyrolysis furnace 1 is connected to the gasification furnace 3, which is used to pre-pyrolyze the electrode material of the waste lithium battery to produce solid products and volatile gases; the gravity separation device 2 is used to gravity separate the solid product to separate the aluminum foil and the copper foil from the solid product, and obtain the solid residue after the aluminum foil and the copper foil are separated; the feed port on the gasification furnace 3 is connected to the gravity separation device 2, and the gasification furnace 3 is provided with a water A steam inlet, wherein the water vapor inlet is used to introduce water vapor into the gasifier 3, and the gasifier 3 is used to gasify the solid residue, the volatile gas and the water vapor simultaneously, so that the volatile gas and the water vapor react with the solid residue to obtain recyclable solids and combustible gas, and to fix the fluorine in the electrode material; the cooling and discharging mechanism 4 is connected to the gasifier 3, and is used to recover the recyclable solids; the absorption device 5 is connected to the combustible gas outlet on the gasifier 3, and is used to recover the combustible gas.

[0061] In one embodiment, the recycling system for waste lithium battery electrode materials further includes a feeding mechanism 6 .

[0062] Specifically, the feeding mechanism 6 is connected to the feeding port at the upper part of the pre-pyrolysis furnace 1 , and is used to feed the electrode materials of the waste lithium batteries into the pre-pyrolysis furnace 1 so that the pre-pyrolysis furnace 1 pre-pyrolyzes them.

[0063] In one embodiment, the recycling system for waste lithium battery electrode materials further includes a residue collection system.

[0064] Specifically, the residue collection system is connected to the lower part of the gravity separation device 2 and is used to collect the solid residue generated after the gravity separation device 2 has gravity separated the solid product.

[0065] In one embodiment, the waste lithium battery electrode material recovery system further includes a first combustion chamber 7 and a second combustion chamber 8 .

[0066] Specifically, the first combustion chamber 7 is connected to the pre-pyrolysis furnace 1 and the absorption device 5 respectively, and is used to burn the combustible gas to provide heat for the pre-pyrolysis furnace 1; the second combustion chamber is connected to the gasification furnace 3, and clean fuel is provided therein for providing heat for the gasification furnace 3.

[0067] It should be noted that the clean fuel refers to a fuel that can produce high calorific value when burned without polluting the environment.

[0068] In one embodiment, the recycling system for waste lithium battery electrode materials further includes a dust removal device 9 .

[0069] Specifically, the dust removal device 9 is disposed between the absorption device 5 and the first combustion chamber 7, and is used for performing dust removal on the combustible gas.

[0070] Preferably, the dust removal device 9 is a cyclone dust collector or an electrostatic dust collector.

[0071] In one embodiment, the waste lithium battery electrode material recovery system further includes a flue gas purification system 10 .

[0072] Specifically, the flue gas purification system 10 is connected to the flue gas outlet of the pre-pyrolysis furnace 1 and is used for purifying the flue gas discharged from the flue gas outlet.

[0073] In one embodiment, the recycling system for waste lithium battery electrode materials further includes a purification device 11 for purifying residual tar and pollutant gases in the combustible gas.

[0074] Specifically, the purification device 11 is disposed between the dust removal device 9 and the first combustion chamber 7 , and is used for purifying the combustible gas after the dust removal treatment by the dust removal device 9 .

[0075] In one embodiment, the flue gas outlet of the pre-pyrolysis furnace 1 is connected to the water vapor inlet of the gasification furnace 3 to provide the water vapor into the gasification furnace 3 .

[0076] In one embodiment, the recycling system for waste lithium battery electrode materials further includes a water leaching device 12 through which CO2 is passed, for dissolving soluble lithium salts.

[0077] Specifically, the water leaching device 12 is connected to the cooling and discharging mechanism 4, and is used to perform water leaching treatment on the recyclable solid under the condition of CO2 introduction, so as to separate the soluble lithium salt and insoluble substances in the recyclable solid.

[0078] In one embodiment, the flue gas outlet on the gasifier 3 is connected to the water extraction device 12 to provide CO 2 for the water extraction device 12 .

[0079] It should be noted that the flue gas discharged from the flue gas outlet of the gasifier 3 contains a large amount of CO 2 .

[0080] In one embodiment, the absorption device 5 is filled with any one or a combination of the following chemical absorbents: lime (CaO), slaked lime (Ca(OH)2), modified Ca(OH)2, dolomite calcined product, sodium carbonate, and caustic soda.

[0081] It should be noted that the above-mentioned cooling and discharging mechanism 4, feeding mechanism 6, absorption device 5, flue gas purification system 10, purification device 11 and water extraction device 12 are all common structures in the field, and their specific working principles and structural connection relationships are not used as conditions to limit the present invention, so they will not be described in detail one by one here.

[0082] It should be noted that the recycling system for waste lithium battery electrode materials of the present invention can implement the recycling method for waste lithium battery electrode materials of the present invention, but the implementation device of the recycling method for waste lithium battery electrode materials of the present invention includes but is not limited to the structure of the recycling system for waste lithium battery electrode materials listed in this embodiment, and all structural deformations and replacements of the prior art made according to the principles of the present invention are included in the protection scope of the present invention.

[0083] It should be noted that the method and system for recycling waste lithium battery electrode materials can improve the recovery rate of valuable metals, enhance the leaching efficiency, and reduce the generation of fluorine-containing wastewater, which is based on the following principles:

[0084] (1) The solid residue contains pyrolytic carbon produced by pyrolysis of PVDF, conductive additive carbon black, and graphite in the anode material. According to thermodynamic analysis (Mao JK, Li J, Xu Z. Coupling reactions and collapsing model in the roasting process of recycling metals from LiCoO2 batteries[J]. Journal of Cleaner Production, 2018, 205(PT.1-1162):923-929.), when the temperature is higher than 419K, the carbon thermal reduction reaction will occur spontaneously, and the high-valent metal (Co 3+ ) is reduced to a low-valent metal (Co 2+ ), the reaction is as follows:

[0085] 4LiCoO2+C→Li2O+Li2CO3+4CoO (1)

[0086] Li2O+2CoO+C→2Co+Li2CO3 (2)

[0087] Secondly, the volatile gas contains hydrogen fluoride (HF) produced by the pyrolysis of PVDF. HF has a synergistic effect on the reduction of high-valent metals in the cathode material (Zhang T, He Y, Wang F, et al. Surface analysis of cobalt-enriched crushed products of spent lithium-ion batteries by X-ray photoelectron spectroscopy [J]. Separation and Purification Technology, 2014, 138: 21-27.), and the reaction is as follows:

[0088] 2LiCoO2+4HF→F2+2CoO+2LiF+2H2O (3)

[0089] (2) As shown in reaction (3), HF will generate lithium fluoride (LiF) after reaction; in addition, HF in the volatile gas will also react with the reduction product Li2CO3 to generate LiF, and the reaction is as follows:

[0090] Li2CO3+HF→LiF+CO2+H2O (4)

[0091] Through the above reaction, the high-valent metal is reduced to a low-valent state, which is beneficial to the subsequent leaching and purification. Secondly, HF fixes fluorine in LiF through reaction (3) and reaction (4), and exists in the form of valuable LiF, thereby effectively reducing the amount of HF gas to be processed.

[0092] (3) In the subsequent separation and purification process, after the reduction reaction, the Li in the recoverable solid mainly exists in the form of Li2CO3 (lithium carbonate) and LiF. Due to the huge difference in solubility between the two, Li2CO3 can be separated preferentially by simple water leaching; however, the solubility of lithium carbonate is only 13.3 g L at 20 °C. -1 In order to improve its solubility, a carbonated water leaching process is used (Yi WT, Yan CY, Ma PH, et al.Refining of crude Li2CO3 via slurry phase dissolution using CO2[J].Separation and Purification Technology, 2007, 56(3):241-248.), and the reaction is as follows:

[0093] Li2CO3(s)+H2O(aq)+CO2(g)→2LiHCO3(aq) (5)

[0094] Through the above reaction, Li2CO3 can be converted into more soluble LiHCO3 (lithium bicarbonate), obtaining a high lithium extraction rate at a lower liquid-to-solid ratio.

[0095] The following specific examples are used to further verify the method and system for recycling waste lithium battery electrode materials of the present invention.

[0096] Embodiment 1

[0097] The electrode material obtained after pretreatment of the waste lithium batteries (cathode active material LiCoO2) of mobile phones and laptops is fed into the pre-pyrolysis furnace 1 by the feeding mechanism 6; in the pre-pyrolysis furnace 1, the pyrolysis temperature is controlled at 550°C, and the pyrolysis time is 20min; the solid product obtained by pyrolysis is removed by the gravity selection device 2 after the bulk collector material aluminum foil and copper foil (the aluminum foil and copper foil are recyclable) are obtained to obtain a solid residue, which is fed into the gasification furnace 3 with an operating temperature of 700°C; at the same time, the volatile gas generated in the pre-pyrolysis furnace 1 and the water vapor added from the outside are also fed into the gasification furnace 3 to contact and react with the solid residue for 30min (the amount of water vapor introduced per unit time is proportional to the electrode material transportation time). The mass ratio of the amount is 0.3:1); the gasification reaction in the gasifier 3 generates recyclable solids and combustible gas; after the recyclable solids are cooled and discharged, the commonly used hydrometallurgical methods can be used to further extract valuable metals such as Li and Co therein; and the generated combustible gas is sent to the alkaline absorption device 5 filled with modified Ca(OH)2, and the recommended calcium-fluorine molar ratio (Ca / F) is 1:2, to remove the remaining HF and other acidic gases; then the fly ash and dust in the gas are intercepted and collected by the dust removal device 9; then, the combustible gas enters the first combustion chamber 7 for combustion, and the obtained high-temperature flue gas is sent to the flue gas inlet of the pre-pyrolysis furnace 1 for heating, and after the heating is completed, it is sent to the flue gas purification system 10 and discharged into the atmosphere.

[0098] After testing and analysis, the main components of the recyclable solid are Co, CoO, Li2CO3, LiF and C, among which the carbon content is 10wt%, 52% of the fluorine is fixed in LiF, and more than 50% of the fluorine in the electrode material is fixed and recovered; 47% of the fluorine is fixed by the absorption device 5, and only 1% of the fluorine enters the wastewater; the recovery rate of valuable metals (Li and Co) is greater than 98wt%.

[0099] When the flue gas discharged from the flue gas outlet on the pre-pyrolysis furnace 1 is used as water vapor and passed into the gasification furnace 3 to react with the solid residue and volatile gas, and the flue gas discharged from the gasification furnace 3 is used to provide CO2 to the water leaching device 12, the flue gas is sent to the gasification furnace 3 to contact and react with the volatile gas and solid residue for 30 minutes to generate combustible gas and recoverable solid; the combustible gas is absorbed by the absorption device 5 equipped with modified Ca(OH)2 and the dust removal device 9 (using a cyclone dust collector) is used for dust removal, and then sent to the first combustion chamber 7 through the purification device 11; the recoverable solid is cooled and discharged by the cooling and discharging mechanism 4, and then sent to the water leaching device 12 with CO2 to separate the soluble lithium salt (Li2CO3) and the insoluble matter; wherein the main components of the insoluble matter are Co, CoO, LiF and C.

[0100] It should be noted that the weakly acidic environment increases the solubility of Li2CO3 (>27gL -1 ), which increases the Li leaching efficiency.

[0101] Embodiment 2

[0102] The electrode material 1 obtained after pretreatment of the waste 18650 power lithium battery (cathode active material LiMn2O4) is fed into the pre-pyrolysis furnace 1 by the feeding mechanism 6; in the pre-pyrolysis furnace 1, the pyrolysis temperature is controlled at 450°C, and the pyrolysis time is 25 minutes; the solid product obtained by pyrolysis is removed by the gravity selection device 2 to remove the bulk collector material aluminum foil and copper foil and the solid residue is obtained after recovery, and is fed into the gasification furnace 3 with an operating temperature of 600°C; at the same time, the volatile gas generated in the pre-pyrolysis furnace 1 and the flue gas discharged from the flue gas outlet on the pre-pyrolysis furnace 1 are also fed into the gasification furnace 3 as water vapor to contact and react with the solid residue for 35 minutes; the gasification reaction in the gasification furnace 3 generates recyclable solids and combustible gas; the recyclable solids can be discharged after cooling The commonly used hydrometallurgical methods are used to further extract the valuable metal elements such as metal Li and Mn; the generated combustible gas is sent to an alkaline absorption device 5 filled with flake caustic soda, and the recommended sodium-fluorine molar ratio (Na / F) is 1:1 to remove the remaining acidic gases such as HF; then the fly ash and dust in the gas are intercepted and collected by a dust removal device 9 (using a cyclone dust collector); then, it is sent to the first combustion chamber 7 through a purification device 11; and the recyclable solid is cooled and discharged by a cooling and discharging mechanism 4 and then sent to a water leaching device 12 with CO2 to separate soluble lithium salts (Li2CO3) and insoluble substances; among them, the main components of the insoluble substances are LiF, MnO and C, which can be further separated and purified by commonly used hydrometallurgical methods.

[0103] According to the test and analysis, the carbon content in the recoverable solid is 8wt%, 55% of the fluorine is fixed in LiF, 43.5% of the fluorine is fixed by the absorption device 5, and the recovery rate of valuable metals (Li and Mn) is greater than 98wt%.

[0104] Embodiment 3

[0105] The ternary lithium battery (cathode active material LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2) The electrode material obtained after pretreatment is fed into the pre-pyrolysis furnace 1 by the feeding mechanism 6; in the pre-pyrolysis furnace 1, the pyrolysis temperature is controlled at 360°C, and the pyrolysis time is 30min; the solid product obtained by pyrolysis is removed by the gravity selection device 2 to remove the bulk collector material aluminum foil and copper foil and the solid residue is recovered and fed into the gasification furnace 3 with an operating temperature of 750°C; at the same time, the volatile gas generated in the pre-pyrolysis furnace 1 and the water vapor added from the outside are also fed into the gasification furnace 3 to contact and react with the solid residue for 30min (the mass ratio of the water vapor introduction amount to the electrode material delivery amount per unit time is 0.5:1); the gasification reaction in the gasification furnace 3 generates Recyclable solids and combustible gases are generated; after the recyclable solids are cooled and discharged, valuable metals such as Li, Ni, Co and Mn can be further extracted by common hydrometallurgical methods; the generated combustible gases are sent to an alkaline absorption device 5 filled with dolomite calcined products, and the recommended calcium-fluorine molar ratio (Ca / F) is 2:1, to remove the remaining acidic gases such as HF; then, the fly ash and dust in the gas are intercepted and collected by a dust removal device 9 (using an electrostatic precipitator); then, the combustible gases enter the first combustion chamber 7 for combustion, and the obtained high-temperature flue gas is sent to the flue gas inlet of the pre-pyrolysis furnace 1 for heating, and after the heating is completed, it is sent to the flue gas purification system 10 and discharged into the atmosphere.

[0106] After testing and analysis, the main components of the recyclable solid are Co, NiO, CoO, Li2CO3, LiF, MnO and C, among which the carbon content is 7wt%, 51% of the fluorine is fixed in LiF, 47% of the fluorine is fixed by the absorption device, and the recovery rate of valuable metals (Li, Ni, Co and Mn) is greater than 98wt%.

[0107] In summary, the recycling method and system of waste lithium battery electrode materials of the present invention, compared with the prior art, in the process of recycling waste lithium batteries, the present invention utilizes the gas produced by the gasifier for heating, thereby saving heating energy consumption; utilizes low-temperature pre-pyrolysis and the gasifier to reduce the volatilization of valuable metals in the recycling process, and utilizes the special atmosphere and absorption device in the gasifier to reduce the discharge of fluorine-containing wastewater, thereby effectively realizing the resource and harmless utilization of waste lithium batteries; the positive electrode active material of the waste lithium battery can be completely detached and separated from the aluminum foil due to the elimination of the binder, and the synergistic effect of pyrolytic carbon, HF, additive carbon black and graphite in the reduction process in the gasifier can be used to realize the high-valent metal Co in the positive electrode material of the waste lithium battery. 3+Reduction to a low-valent state makes the subsequent hydrometallurgical treatment process convenient and simple; the present invention can reuse the pyrolysis products of the organic binder after combustion, thereby reducing the operating energy consumption; the reduction process of the present invention can make fluorine react with LiCoO2 and be fixed in lithium fluoride with utilization value, thereby realizing the recovery and utilization of fluorine, and through dry absorption of the remaining hydrogen fluoride in the gas product, the amount of fluorine-containing wastewater generated by the subsequent flue gas purification system can be effectively reduced; at the same time, gasification can effectively reduce the carbon content in the solid residue, thereby reducing the separation burden in the subsequent hydrometallurgical process; therefore, the present invention effectively overcomes various shortcomings in the prior art and has a high industrial utilization value.

[0108] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for recycling waste lithium battery electrode materials, characterized in that: The following steps are involved: Pre-processing the waste lithium batteries to obtain electrode materials of the waste lithium batteries; Pre-pyrolyzing the electrode material to produce solid products and volatile gases, wherein the working temperature corresponding to the pre-pyrolysis is 350-550° C.; Reselecting the solid product to separate the aluminum foil and the copper foil and recovering them to obtain a solid residue after the aluminum foil and the copper foil are separated; The solid residue, the volatile gas and the water vapor introduced from the outside are gasified simultaneously, so that the volatile gas and the water vapor react with the solid residue to obtain recyclable solid and combustible gas, and to fix the fluorine in the electrode material, wherein the working temperature corresponding to the gasification is 600-750°C.

2. The method for recycling waste lithium battery electrode materials according to claim 1, characterized in that: The working time corresponding to the pre-pyrolysis is 20-30 minutes; the combustible gas is used to provide heat for the pre-pyrolysis; and the reaction time of the volatile gas and the water vapor with the solid residue is 30-50 minutes.

3. The method for recycling waste lithium battery electrode materials according to claim 1, characterized in that: Using a bouncing screen to reselect the solid product, so as to separate the aluminum foil and the copper foil from the solid product for recovery; The solid residue includes any one or a combination of the following: carbon, cobalt oxide, manganese oxide, nickel oxide, cobalt lithium oxide and nickel; The components of the recyclable solid include any one or a combination of the following: lithium carbonate, manganese oxide, carbon, lithium fluoride, cobalt, nickel oxide, and cobalt oxide; wherein the weight fraction of the carbon is less than 10%.

4. A recycling system for waste lithium battery electrode materials, characterized in that: include: Pre-pyrolysis furnace, gravity separation device, gasification furnace, cooling and discharging mechanism and absorption device; The discharge port on the pre-pyrolysis furnace is connected to the gravity separation device, and the volatile gas outlet on the pre-pyrolysis furnace is connected to the gasification furnace, which is used to pre-pyrolyze the electrode material of the waste lithium battery to produce solid products and volatile gases, wherein the working temperature corresponding to the pre-pyrolysis is 350-550°C; The gravity separation device is used to gravity separate the solid product to separate and recover the aluminum foil and copper foil from the solid product, and obtain the solid residue after the aluminum foil and copper foil are separated; The feed inlet on the gasifier is connected to the gravity separation device. The gasifier is provided with a water vapor inlet, which is used to introduce water vapor into the gasifier. The gasifier is used to gasify the solid residue, the volatile gas and the water vapor at the same time, so that the volatile gas and the water vapor react with the solid residue to obtain recyclable solid and combustible gas, and to fix the fluorine in the electrode material, wherein the working temperature corresponding to the gasification is 600-750°C; The cooling and discharging mechanism is connected to the gasifier and is used to recover the recyclable solids; The absorption device is connected to the combustible gas outlet on the gasifier and is used to recover the combustible gas.

5. The recycling system of waste lithium battery electrode materials according to claim 4, characterized in that: Also includes: A first combustion chamber and a second combustion chamber; wherein, The first combustion chamber is connected to the pre-pyrolysis furnace and the absorption device respectively, and is used to burn the combustible gas to provide heat for the pre-pyrolysis furnace; The second combustion chamber is connected to the gasifier and is provided with clean fuel for providing heat to the gasifier.

6. The recycling system of waste lithium battery electrode materials according to claim 4, characterized in that: Also includes: Dust removal device and flue gas purification system; among which, The dust removal device is arranged between the absorption device and the first combustion chamber, and is used for performing dust removal on the combustible gas; The dust removal device adopts a cyclone dust collector or an electrostatic dust collector; The flue gas purification system is connected to the flue gas outlet of the pre-pyrolysis furnace and is used for purifying the flue gas discharged from the flue gas outlet.

7. The recycling system of waste lithium battery electrode materials according to claim 6, characterized in that: Also includes: Purification device; the purification device is arranged between the dust removal device and the first combustion chamber, and is used to purify the combustible gas after the dust removal treatment by the dust removal device.

8. The recycling system of waste lithium battery electrode materials according to claim 4, characterized in that: The flue gas outlet of the pre-pyrolysis furnace is connected to the water vapor inlet for providing the water vapor to the gasification furnace.

9. The recycling system of waste lithium battery electrode materials according to claim 4, characterized in that: Also includes: A water leaching device with CO2 passing through it; the water leaching device is connected to the cooling and discharging mechanism, and is used to perform water leaching treatment on the recyclable solid under the condition of CO2 passing through it, so as to separate the soluble lithium salt and insoluble matter in the recyclable solid.

10. The recycling system of waste lithium battery electrode materials according to claim 4, characterized in that: The absorption device is filled with any one or a combination of the following chemical absorbents: lime CaO, slaked lime Ca(OH)2, modified Ca(OH)2, dolomite calcined product, sodium carbonate, and caustic soda flakes.

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