A pretreatment method for recycling waste lithium batteries

Abstract

The present application specifically discloses a pretreatment method for recycling waste lithium batteries, which includes four combined processes: low-temperature evaporation pre-pyrolysis in the first rotary kiln, gas-phase absorption solid fluorine and solid phosphorus in the second rotary kiln, medium-temperature deep defluorination in the third rotary kiln, and purification and cooling in the fourth rotary kiln. In the first rotary kiln, the waste heat of the fourth rotary kiln is fully utilized to evaporate the low-boiling point organic solvent and decompose the low-cracking temperature fluorine-containing substances in the waste lithium battery black powder raw material A; in the second rotary kiln, the solid fluorine and solid phosphorus raw material B is used to absorb and solidify the fluorine and phosphorus in the tail gas G1, and water vapor is generated; in the third rotary kiln, the catalytic thermal cracking tail gas G2 generates hydrogen atoms to react with the fluorine-containing substances in the thermal cracking battery black powder C to generate hydrogen fluoride, and the tail gas G3 rich in hydrogen fluoride is discharged from the third rotary kiln to obtain the battery black powder D after deep defluorination. Therefore, the present application realizes the deep defluorination of the waste lithium battery black powder raw material.

Description

Technical Field

[0001] The present application belongs to the technical field of lithium battery recycling, and in particular, relates to a pretreatment method for recycling waste lithium batteries. Background Art

[0002] In recent years, lithium batteries have been widely used in the automotive power battery market and the electrochemical energy storage market, and have maintained a relatively high annual growth rate. As the life of the lithium batteries installed in the early stage comes to an end and they will gradually enter the retirement period, lithium batteries contain toxic and harmful substances such as fluorine, organic solvents, and heavy metals, which must be recycled and processed in a standardized manner. At the same time, waste lithium batteries are also valuable "urban mines", which are of great significance to the closed-loop development of the lithium battery industry chain.

[0003] In the process of recycling and reusing waste lithium batteries, one of the key processes at the front end is the pretreatment of waste lithium battery black powder. Its purpose is to remove organic solvents, fluorine-free binders, fluorine-containing electrolytes, fluorine-containing binders or additives contained in the waste lithium battery black powder. In particular, the removal of fluorine-containing substances is a difficulty and pain point in the industry.

[0004] At present, the pretreatment method of waste lithium battery black powder is generally in the form of thermal cracking, that is, the organic solvent, non-fluorine-containing binder, fluorine-containing electrolyte, fluorine-containing binder or additive contained in the waste lithium battery black powder is cracked under the action of temperature, and part of the cracking product is in the gas phase, through which part of the harmful fluorine-containing substances originally contained in the waste lithium battery black powder are removed. However, the fluorine removal rate of the above-mentioned pretreatment method of waste lithium battery black powder is not high, which leads to the problem of high cost and poor economic efficiency of the pretreatment defluorination method.

[0005] Therefore, there is an urgent need to develop a high defluorination rate, high efficiency, and low-cost pretreatment method for waste lithium battery black powder, so as to maximize the recycling value of waste lithium iron phosphate batteries. Summary of the invention

[0006] This application is made in view of the above technical problems and aims to provide a pretreatment method for recycling waste lithium batteries with high defluorination rate, high efficiency and low cost.

[0007] In order to solve the above technical problems, the present application provides a waste lithium battery recycling pretreatment method, which includes four combined processes: low-temperature evaporation pre-pyrolysis in a first rotary kiln, gas phase absorption of fluorine and phosphorus fixation in a second rotary kiln, medium-temperature deep defluorination in a third rotary kiln, and purification cooling in a fourth rotary kiln, wherein:

[0008] Low-temperature evaporation and pyrolysis, the waste lithium battery black powder raw material A is transported to the first rotary kiln with a temperature of T1 at a rate of M kg / hour, and the tail gas G4 with a temperature of T4 discharged from the fourth rotary kiln is introduced in a countercurrent manner with the waste lithium battery black powder raw material A to obtain the tail gas G1 and battery black powder C, wherein T1 and T4 satisfy: T1-100≤T4≤T1;

[0009] Gas-phase absorption of fixed fluorine and fixed phosphorus, transporting the fixed fluorine and fixed phosphorus raw material B to the second rotary kiln at a temperature of T2 at a rate of N kg / hour, and introducing the tail gas G1 at a temperature of T1 discharged from the first rotary kiln in a countercurrent manner to the fixed fluorine and fixed phosphorus raw material B, to obtain tail gas G2 and fixed fluorine slag, wherein T2 satisfies: 120℃≤T2≤450℃, and T1 satisfies: 120℃≤T1≤300℃;

[0010] Medium-temperature deep defluorination, the battery black powder C obtained after low-temperature evaporation and pyrolysis in the first rotary kiln is transported to the third rotary kiln at a temperature of T3, and the tail gas G2 at a temperature of T2 discharged from the second rotary kiln is introduced in a countercurrent manner to the battery black powder C to obtain the tail gas G3 and the battery black powder D after deep defluorination, wherein T3 satisfies: 500℃≤T3≤800℃;

[0011] After purification and cooling, the battery black powder D after deep defluorination in the third rotary kiln is transported to the fourth rotary kiln, and an inert gas is introduced in a countercurrent manner to the battery black powder D to obtain tail gas G4 and battery black powder E;

[0012] Among them, the fluorine-fixing and phosphorus-fixing raw material B and the waste lithium battery black powder raw material A meet the following requirements: , where N is the delivery rate of the solid fluorine and solid phosphorus raw material B, in kg / hour, M is the delivery rate of the waste lithium battery black powder raw material, in kg / hour, and a is the mass fraction of LiPF6 in the waste lithium battery black powder raw material.

[0013] In some embodiments, the low-temperature evaporation and pyrolysis treatment time of the waste lithium battery black powder raw material A in the first rotary kiln is 10-240 minutes, the gas phase absorption and solid fluorine and solid phosphorus treatment time of the tail gas G1 in the second rotary kiln is 1-30 minutes, and the deep defluorination treatment time of the battery black powder C in the third rotary kiln is 10-180 minutes.

[0014] Compared with the prior art, the waste lithium battery recycling pretreatment method provided in this application has the following beneficial technical effects:

[0015] 1. The present application adopts a combined process method, and realizes the deep defluorination of waste lithium battery black powder raw materials through four combined process steps of low-temperature evaporation pyrolysis, pre-absorption solidification, enhanced cracking defluorination and purification cooling. In the low-temperature evaporation pyrolysis, the waste heat of the tail gas G4 is used to perform low-temperature evaporation and decomposition on the waste lithium battery black powder raw materials, so that the low-boiling point organic solvent in the waste lithium battery black powder raw materials evaporates and the low-cracking temperature fluorine-containing substances are decomposed; in the pre-absorption solidification, the fluorine and phosphorus in the fluorine-containing and phosphorus-containing substances in the tail gas G1 are absorbed and solidified by the fluorine-fixing and phosphorus-fixing raw material B, and the tail gas G2 containing water vapor is output, which can greatly reduce the fluorine in the tail gas G2. On the other hand, it can also increase the concentration of water vapor in the tail gas G2. The reduction in the concentration of fluorine and phosphorus is equivalent to reducing the concentration of fluoride, the reaction product of the defluorination reaction, which is beneficial to promoting the defluorination reaction in the medium-temperature deep defluorination process. At the same time, it also reduces the side reaction of fluorine and phosphorus in the tail gas G2 with the battery black powder C in the subsequent deep defluorination reaction, that is, it reduces the generation of more stable metal fluorides or phosphides; the increase in water vapor concentration is beneficial to the catalytic pyrolysis of more hydrogen atoms and hydrogen protons in the medium-temperature deep defluorination process, which can effectively promote the combination of hydrogen atoms and hydrogen protons with fluorine to generate hydrogen fluoride gas, thereby achieving the effect of deep defluorination;

[0016] 2. This application adopts a combined process method to shorten the defluorination process time while ensuring a high defluorination rate. The fastest defluorination pretreatment time is only 30-40 minutes, so this application also has the characteristics of high efficiency;

[0017] 3. The pretreatment method provided in the present application does not introduce new inorganic anions and metal cations, which is very beneficial to reduce the difficulty of impurity removal, purification and separation of the pretreated lithium battery black powder in the subsequent recovery process. Moreover, this method only uses inert gas and cheap raw materials such as solid fluorine and solid phosphorus raw materials B, which reduces the cost of raw materials; at the same time, the low-temperature evaporation pyrolysis process also makes full use of the waste heat of the tail gas G4 after purification and cooling, effectively reducing energy consumption.

[0018] In summary, the waste lithium battery recycling pretreatment method provided in the present application has the characteristics of high defluorination rate, high efficiency and low cost, and has significant cost advantages compared with existing traditional process methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1A flow chart showing a method for preprocessing waste lithium batteries for recycling in some embodiments of the present application is shown.

[0021] Figure 2 The process flow chart of the waste lithium battery recycling pretreatment method in some embodiments of the present application is shown.

[0022] Figure 3 A schematic diagram of a device corresponding to a pretreatment method in some embodiments of the present application is shown. DETAILED DESCRIPTION

[0023] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0024] If there is no special explanation, the "include" and "comprising" mentioned in this application are open-ended or closed-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0025] refer to Figure 1-Figure 3 As shown, the embodiment of the present application provides a waste lithium battery recycling pretreatment method, the method comprising four combined processes of low-temperature evaporation pre-pyrolysis in a first rotary kiln, gas phase absorption solid fluorine and solid phosphorus in a second rotary kiln, medium-temperature deep defluorination in a third rotary kiln, and purification cooling in a fourth rotary kiln, wherein:

[0026] Low-temperature evaporation and pyrolysis, the waste lithium battery black powder raw material A is transported to the first rotary kiln with a temperature of T1 at a rate of M kg / hour, and the tail gas G4 with a temperature of T4 discharged from the fourth rotary kiln is introduced in a countercurrent manner with the waste lithium battery black powder raw material A to obtain the tail gas G1 and battery black powder C, wherein T1 and T4 satisfy: T1-100≤T4≤T1;

[0027] Gas-phase absorption of fixed fluorine and fixed phosphorus, transporting the fixed fluorine and fixed phosphorus raw material B to the second rotary kiln at a temperature of T2 at a rate of N kg / hour, and introducing the tail gas G1 at a temperature of T1 discharged from the first rotary kiln in a countercurrent manner to the fixed fluorine and fixed phosphorus raw material B, to obtain the tail gas G2 and fixed fluorine slag (BS), wherein T2 satisfies: 120℃≤T2≤450℃, and T1 satisfies: 120℃≤T1≤300℃;

[0028] Medium-temperature deep defluorination, the battery black powder C obtained after low-temperature evaporation and pyrolysis in the first rotary kiln is transported to the third rotary kiln at a temperature of T3, and the tail gas G2 at a temperature of T2 discharged from the second rotary kiln is introduced in a countercurrent manner to the battery black powder C to obtain the tail gas G3 and the battery black powder D after deep defluorination, wherein T3 satisfies: 500℃≤T3≤800℃;

[0029] After purification and cooling, the battery black powder D after deep defluorination in the third rotary kiln is transported to the fourth rotary kiln, and an inert gas is introduced in a countercurrent manner to the battery black powder D to obtain tail gas G4 and battery black powder E;

[0030] Among them, the fluorine-fixing and phosphorus-fixing raw material B and the waste lithium battery black powder raw material A meet the following requirements: , where N is the delivery rate of the solid fluorine and solid phosphorus raw material B, in kg / hour, M is the delivery rate of the waste lithium battery black powder raw material, in kg / hour, and a is the mass fraction of LiPF6 in the waste lithium battery black powder raw material.

[0031] In the above embodiment, it should be noted that in the initial stage of pretreatment of the waste lithium battery black powder raw material A, since there is no tail gas G4 in the system, at this time, the waste lithium battery black powder raw material A is transported to the first rotary kiln with a temperature of T1 at a rate of M kg / hour, and the low boiling point organic solvent in the waste lithium battery black powder raw material A is evaporated and the low cracking temperature fluorine-containing substances in the waste lithium battery black powder raw material are decomposed based on the temperature in the first rotary kiln; when the tail gas G4 is generated in the system, the tail gas G4 is passed into the first rotary kiln in a countercurrent manner to the waste lithium battery black powder raw material A, and the waste heat of the tail gas G4 is used to evaporate the low boiling point organic solvent in the waste lithium battery black powder raw material and decompose the low cracking temperature fluorine-containing substances in the waste lithium battery black powder raw material, thereby achieving full utilization of the system waste heat and effectively reducing energy consumption.

[0032] Among them, the evaporation and pyrolysis treatment time of the waste lithium battery black powder raw material A in the first rotary kiln can be selected as any value between 10 and 240 minutes. For example, it can be 10 minutes, 60 minutes, 110 minutes, 160 minutes, 210 minutes, 240 minutes, etc.

[0033] The temperature T1 may be any value between 120-300°C, for example, 120°C, 150°C, 180°C, 210°C, 240°C, 270°C, 300°C, etc.

[0034] Among them, the decomposition chemical reaction formula of the low cracking temperature fluorine-containing substance in the waste lithium battery black powder raw material A is as follows:

[0035] (1)

[0036] Under normal pressure, the boiling points of organic solvents such as dimethyl carbonate (DMC) are 90°C, dimethyl carbonate (DEC) is 125.8°C, ethyl methyl carbonate (EMC) is 107°C, ethylene carbonate (EC) is 243°C, and propylene carbonate (PC) is 241.7°C. Therefore, when the temperature T1 of the first rotary kiln is greater than the boiling point of the organic solvent, the organic solvent can evaporate in large quantities and enter the tail gas G1.

[0037] In the second rotary kiln, the fluorine and phosphorus in the fluorine-containing substances and phosphorus-containing substances in the tail gas G1 can be absorbed and solidified by using the solid fluorine and solid phosphorus raw material B, and the tail gas G2 containing water vapor and solid fluorine slag are obtained. The water vapor in the tail gas G2 is catalytically thermally cracked in the third rotary kiln to generate hydrogen atoms, and the generated hydrogen atoms can react with the fluorine obtained by thermally cracking the fluorine-containing substances in the battery black powder C to generate hydrogen fluoride. The tail gas G3 rich in hydrogen fluoride is discharged from the third rotary kiln, and the battery black powder D after deep defluorination is obtained. In the fourth rotary kiln, the residual tail gas G3 adsorbed in the battery black powder D is carried and discharged by the inert gas, and the battery black powder D is gradually cooled. The inert gas is heated and then returned to the first rotary kiln for reuse, which effectively reduces energy consumption. Therefore, the waste lithium battery recycling pretreatment method provided by the present application has the characteristics of high defluorination rate, high efficiency and low cost, and has significant cost advantages compared with the existing traditional process methods.

[0038] Among them, the temperature T2 can be any value between 120-450°C, and illustratively, it can be 120°C, 170°C, 220°C, 270°C, 320°C, 370°C, 450°C, etc.; the solidification time of solid fluorine and solid phosphorus in the second rotary kiln can be any value between 10-30 minutes, and illustratively, it can be 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, etc.; in this embodiment, the solid fluorine and solid phosphorus raw material is calcium hydroxide, which is widely available and low in cost.

[0039] In the second rotary kiln, the fluorine-fixing and phosphorus-fixing raw materials react with the tail gas G1 to fix fluorine and phosphorus. The chemical reaction formula is as follows:

[0040] (2)

[0041] It can be seen that the tail gas G2 includes the water vapor generated in reaction formula (2) and the organic solvent gas evaporated in the first rotary kiln.

[0042] Among them, the temperature T3 can be any value between 500-800°C, and for example, it can be 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, etc.; the treatment time of the battery black powder C in the third rotary kiln can be any value between 10-180 minutes, and for example, it can be 10 minutes, 40 minutes, 70 minutes, 100 minutes, 130 minutes, 160 minutes, 180 minutes, etc.

[0043] In the third rotary kiln, the water vapor in the tail gas G2 is catalytically cracked to generate hydrogen atoms. The chemical reaction formula of the catalytic cracking of water vapor is as follows:

[0044] (3)

[0045] The hydrogen atoms generated by catalytic cracking can react with the fluorine atoms or fluorine-containing metal fluorides (taking LiF as an example) generated by the cracking of battery black powder C. The chemical reaction formula is as follows:

[0046] (4)

[0047] (5)

[0048] Based on equations (4) and (5), it can be seen that the hydrogen fluoride gas generated by the reaction in the third rotary kiln enters the tail gas G3. In order to prevent the tail gas G3 from polluting the environment, the output tail gas G3 needs to be sent to the tail gas treatment system for absorption treatment and can only be discharged after meeting the standards.

[0049] It should be noted that the first rotary kiln, the second rotary kiln, the third rotary kiln and the fourth rotary kiln all adopt a countercurrent method, which can fully increase the contact area between materials, thereby effectively improving the reaction efficiency or heat exchange efficiency. At the same time, the values ​​of temperature T1 and T4 should be selected under the premise of satisfying T1-100≤T4≤T1.

[0050] The following examples describe the disclosure of the present application in more detail, and these examples are merely illustrative, as it will be apparent to those skilled in the art that various modifications and variations within the scope of the disclosure of the present application are possible. Unless otherwise stated, all reagents and raw materials used in the examples are commercially available or synthesized according to conventional methods, and the instruments and equipment used in the examples are commercially available.

[0051] Example 1

[0052] 1) Low-temperature evaporation pyrolysis: waste lithium battery black powder raw material A containing a LiPF6 mass fraction of a=2.4% and a total fluorine content of 3.4% is transported to the first rotary kiln at a temperature of T1=120°C at a rate of M=100 kg / h, and is introduced into the tail gas G4 with a temperature of T4=150°C discharged from the fourth rotary kiln in a countercurrent manner to the waste lithium battery black powder raw material A. The treatment time of the waste lithium battery black powder raw material A in the first rotary kiln is controlled at 240 minutes; after treatment, the tail gas G1 is discharged from the first rotary kiln, and the temperature of the tail gas G1 is T1=120°C;

[0053] 2) Fluorine and phosphorus fixation by gas phase absorption: The fluorine and phosphorus fixation raw material calcium hydroxide B is transported to the second rotary kiln at a temperature of T2 = 120°C at a rate of N = 10 kg / h, and introduced into the tail gas G1 discharged from the first rotary kiln in a countercurrent manner to the fluorine and phosphorus fixation raw material calcium hydroxide B; in the second rotary kiln, the fluorine and phosphorus in the fluorine-containing and phosphorus-containing substances in the tail gas G1 are absorbed and solidified by the fluorine and phosphorus fixation raw material calcium hydroxide, and the gas phase absorption fluorine and phosphorus fixation treatment time of the tail gas G1 in the second rotary kiln is 30 minutes; the second rotary kiln discharges tail gas G2 containing water vapor, and the temperature of the tail gas G2 is T2 = 120°C, wherein, , satisfying the relationship between the solid fluorine and solid phosphorus raw material B and the waste lithium battery black powder raw material A ;

[0054] 3) Medium-temperature deep defluorination: The battery black powder C obtained after low-temperature evaporation and pyrolysis in the first rotary kiln is transported to the third rotary kiln at a temperature of T3=500°C, and the tail gas G2 discharged from the second rotary kiln is introduced in a countercurrent manner to the battery black powder C; in the third rotary kiln, the water vapor in the tail gas G2 is catalytically cracked to generate hydrogen atoms, and the fluorine-containing substances in the battery black powder C are thermally cracked, and then the generated hydrogen atoms react with the fluorine-containing substances to generate hydrogen fluoride, and the tail gas G3 rich in hydrogen fluoride is discharged from the third rotary kiln and sent to the tail gas treatment system, and the battery black powder D after deep defluorination is obtained; wherein, the deep defluorination treatment time of the battery black powder C in the third rotary kiln is 180 minutes;

[0055] 4) Purification and cooling: The battery black powder D obtained after deep defluorination in the third rotary kiln is transported to the fourth rotary kiln, and an inert gas is introduced in a countercurrent manner to the battery black powder D. In the fourth rotary kiln, the battery black powder D is gradually cooled by the inert gas to obtain battery black powder E. At the same time, the residual tail gas G3 adsorbed in the battery black powder D is carried away by the inert gas to form tail gas G4 with a temperature of T4.

[0056] Example 2

[0057] 1) Low-temperature evaporation pyrolysis: The waste lithium battery black powder raw material A containing a LiPF6 mass fraction of a=3.0% and a total fluorine content of 3.9% is transported to the first rotary kiln with a temperature of T1=220°C at a rate of M=100 kg / h, and is introduced into the tail gas G4 with a temperature of T4=220°C discharged from the fourth rotary kiln in a countercurrent manner with the waste lithium battery black powder raw material A. The treatment time of the waste lithium battery black powder raw material A in the first rotary kiln is controlled at 100 minutes; the tail gas G1 discharged from the first rotary kiln after treatment has a temperature of T1=220°C;

[0058] 2) Fluorine and phosphorus fixation by gas phase absorption: The fluorine and phosphorus fixation raw material calcium hydroxide B is transported to the second rotary kiln at a temperature of T2 = 300°C at a rate of N = 22 kg / h, and is introduced into the tail gas G1 discharged from the first rotary kiln in a countercurrent manner to the fluorine and phosphorus fixation raw material calcium hydroxide B. In the second rotary kiln, the fluorine and phosphorus in the fluorine-containing and phosphorus-containing substances in the tail gas G1 are absorbed and solidified by the fluorine and phosphorus fixation raw material calcium hydroxide B. The gas phase absorption fluorine and phosphorus fixation treatment time of the tail gas G1 in the second rotary kiln is 20 minutes. The second rotary kiln discharges tail gas G2 containing water vapor, and the temperature of the tail gas G2 is T2 = 300°C, wherein, , satisfying the relationship between the solid fluorine and solid phosphorus raw material B and the waste lithium battery black powder raw material A ;

[0059] 3) Medium-temperature deep defluorination: The battery black powder C obtained after low-temperature evaporation and pyrolysis in the first rotary kiln is transported to the third rotary kiln at a temperature of T3=600°C, and the tail gas G2 discharged from the second rotary kiln is introduced in a countercurrent manner to the battery black powder C. In the third rotary kiln, the water vapor in the tail gas G2 is catalytically cracked to generate hydrogen atoms, and the fluorine-containing substances in the battery black powder C are thermally cracked. Then, the generated hydrogen atoms react with the fluorine-containing substances to generate hydrogen fluoride. The tail gas G3 rich in hydrogen fluoride is discharged from the third rotary kiln and sent to the tail gas treatment system to obtain the second battery black powder D after deep defluorination; wherein, the deep defluorination treatment time of the battery black powder C in the third rotary kiln is 80 minutes;

[0060] 4) Purification and cooling: The battery black powder D obtained after deep defluorination in the third rotary kiln is transported to the fourth rotary kiln, and an inert gas is introduced in a countercurrent manner to the battery black powder D; in the fourth rotary kiln, the battery black powder D is gradually cooled by the inert gas to obtain the battery black powder E, and at the same time, the residual tail gas G3 adsorbed in the battery black powder D is carried away by the inert gas to form the tail gas G4 with a temperature of T4.

[0061] Example 3

[0062] 1) Low-temperature evaporation pre-pyrolysis: The waste lithium battery black powder raw material A containing a LiPF6 mass fraction of a=1.5% and a total fluorine content of 2.7% is transported to the first rotary kiln at a temperature of T1=300°C at a rate of M=100 kg / h, and is introduced into the tail gas G4 with a temperature of T4=240°C discharged from the fourth rotary kiln in a countercurrent manner with the waste lithium battery black powder raw material A. The treatment time of the waste lithium battery black powder raw material A in the first rotary kiln is controlled at 10 minutes. After treatment, the tail gas G1 is discharged from the first rotary kiln, and the temperature of the tail gas G1 is T1=260°C;

[0063] 2) Fluorine and phosphorus fixation by gas phase absorption: The fluorine and phosphorus fixation raw material calcium hydroxide B is transported to the second rotary kiln at a temperature of T2 = 450°C at a rate of N = 25 kg / h, and is introduced into the tail gas G1 discharged from the first rotary kiln in a countercurrent manner to the fluorine and phosphorus fixation raw material calcium hydroxide B. In the second rotary kiln, the fluorine and phosphorus in the fluorine-containing and phosphorus-containing substances in the tail gas G1 are absorbed and solidified by the fluorine and phosphorus fixation raw material calcium hydroxide B. The gas phase absorption fluorine and phosphorus fixation treatment time of the tail gas G1 in the second rotary kiln is 10 minutes; the second rotary kiln discharges tail gas G2 containing water vapor, and the temperature of the tail gas G2 is T2 = 450°C, wherein, , satisfying the relationship between the solid fluorine and solid phosphorus raw material B and the waste lithium battery black powder raw material A ;

[0064] 3) Medium-temperature deep defluorination: The battery black powder C obtained after low-temperature evaporation and pyrolysis in the first rotary kiln is transported to the third rotary kiln at a temperature of T3 = 800 ° C, and the tail gas G2 discharged from the second rotary kiln is introduced in a countercurrent manner to the battery black powder C. In the third rotary kiln, the water vapor in the tail gas G2 is catalytically cracked to generate hydrogen atoms, and the fluorine-containing substances in the battery black powder C are thermally cracked. Then, the generated hydrogen atoms react with the fluorine-containing substances to generate hydrogen fluoride. The tail gas G3 rich in hydrogen fluoride is discharged from the third rotary kiln and sent to the tail gas treatment system to obtain the battery black powder D after deep defluorination; wherein, the deep defluorination treatment time of the battery black powder C in the third rotary kiln is 10 minutes;

[0065] 4) Purification and cooling: The battery black powder D obtained after deep defluorination at medium temperature in the third rotary kiln is transported to the fourth rotary kiln, and an inert gas is introduced in a countercurrent manner to the battery black powder D. In the fourth rotary kiln, the battery black powder D is gradually cooled by the inert gas to obtain battery black powder E. At the same time, the residual tail gas G3 adsorbed in the battery black powder D is carried away by the inert gas to form tail gas G4 with a temperature of T4.

[0066] The third battery black powder obtained in Examples 1-3 was respectively taken to test the fluorine content. The test results are shown in Table 1.

[0067] Table 1 Detection results of fluorine content in battery black powder E obtained in Examples 1-3

[0068]

[0069] As can be seen from Table 1, the fluorine content in the battery black powder E obtained in Example 1, Example 2 and Example 3 is all below 0.05%, that is, the defluorination rate of the waste lithium battery black powder is all above 99%. Therefore, the waste lithium battery recycling pretreatment method provided in the present application can effectively remove the fluorine element in the waste lithium battery black powder, and has the characteristics of high defluorination rate, high efficiency and low cost, which provides favorable conditions for the subsequent recycling and treatment of waste lithium battery black powder.

[0070] The above is a detailed introduction to a waste lithium battery recycling pretreatment method provided by the present application. This article uses specific examples to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the core idea of ​​the present application. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

Claims

1. A waste lithium battery recycling pretreatment method, characterized in that: The method comprises four combined processes: low-temperature evaporation and pyrolysis in a first rotary kiln, gas-phase absorption and solidification of fluorine and phosphorus in a second rotary kiln, medium-temperature deep defluorination in a third rotary kiln, and purification and cooling in a fourth rotary kiln, wherein: Low-temperature evaporation and pyrolysis, the waste lithium battery black powder raw material A is transported to the first rotary kiln with a temperature of T1 at a rate of M kg / hour, and the tail gas G4 with a temperature of T4 discharged from the fourth rotary kiln is introduced in a countercurrent manner with the waste lithium battery black powder raw material A to obtain the tail gas G1 and battery black powder C, wherein T1 and T4 satisfy: T1-100≤T4≤T1; Gas-phase absorption of fixed fluorine and fixed phosphorus, conveying the fixed fluorine and fixed phosphorus raw material B to the second rotary kiln at a temperature of T2 at a rate of N kg / hour, introducing the tail gas G1 at a temperature of T1 discharged from the first rotary kiln in a countercurrent manner to the fixed fluorine and fixed phosphorus raw material B, to obtain tail gas G2 and fixed fluorine slag, wherein T2 satisfies: 120°C≤T2≤450°C, T1 satisfies: 120°C≤T1≤300°C, and the fixed fluorine and fixed phosphorus raw material B is calcium hydroxide; Medium-temperature deep defluorination, the battery black powder C obtained after low-temperature evaporation and pyrolysis in the first rotary kiln is transported to the third rotary kiln at a temperature of T3, and the tail gas G2 at a temperature of T2 discharged from the second rotary kiln is introduced in a countercurrent manner to the battery black powder C to obtain the tail gas G3 and the battery black powder D after deep defluorination, wherein T3 satisfies: 500℃≤T3≤800℃; After purification and cooling, the battery black powder D after deep defluorination in the third rotary kiln is transported to the fourth rotary kiln, and an inert gas is introduced in a countercurrent manner to the battery black powder D to obtain tail gas G4 and battery black powder E; Among them, the fluorine-fixing and phosphorus-fixing raw material B and the waste lithium battery black powder raw material A meet the following requirements: , where N is the delivery rate of the solid fluorine and solid phosphorus raw material B, in kg / hour, M is the delivery rate of the waste lithium battery black powder raw material, in kg / hour, and a is the mass fraction of LiPF6 in the waste lithium battery black powder raw material.

2. The waste lithium battery recycling pretreatment method according to claim 1, characterized in that: The low-temperature evaporation and pyrolysis treatment time of the waste lithium battery black powder raw material A in the first rotary kiln is 10-240 minutes, the gas phase absorption and solid fluorine and solid phosphorus treatment time of the tail gas G1 in the second rotary kiln is 1-30 minutes, and the deep defluorination treatment time of the battery black powder C in the third rotary kiln is 10-180 minutes.

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