WO2024045532A1 - Method for recovering and pretreating spent lithium-ion battery - Google Patents

Abstract

Disclosed in the present invention is a method for recovering and pretreating a spent lithium-ion battery. The method comprises: discharging a spent lithium-ion battery, removing an electrolytic solution, and drying same; crushing the dried battery, and subjecting the crushed material to shaking table separation to separately obtain a first mixture containing steel slag, a copper sheet and graphite and a second mixture containing an aluminum foil and a black powder; roasting and screening the second mixture in an inert atmosphere to separate out the aluminum foil and the black powder; subjecting the first mixture to magnetic separation to separate out the steel slag and a third mixture containing the copper sheet and graphite; and roasting and screening the third mixture in an inert atmosphere to separate out the copper sheet and graphite. In the present invention, overall recovery of a spent lithium-ion battery is achieved by means of the procedures of crushing, screening, shaking table separation, magnetic separation, roasting, secondary screening, etc., and the whole process can be completed mechanically without any manual work; and in the whole separation process, physical separation is carried out by utilizing the inherent properties of materials, no chemical reagent is added, and therefore the method is a green and efficient separation method.

Description

Methods for recycling and preprocessing of used lithium-ion batteries Technical field

The invention belongs to the technical field of lithium battery recycling, and specifically relates to a method for recycling and preprocessing of waste lithium ion batteries.

Background technique

With the rapid development of the new energy industry, lithium iron phosphate batteries are widely used in electric vehicles and hybrid vehicles due to their low cost and high safety performance. Generally speaking, the service life of lithium iron phosphate batteries is In 5 to 8 years, lithium iron phosphate will usher in a wave of retirement in recent years. If a large number of used lithium iron phosphate batteries cannot be properly disposed of, it will not only cause serious pollution to the environment, but also cause the loss of scarce lithium resources. Therefore, the recycling and processing of used lithium iron phosphate batteries will be the focus of future research.

The recycling of used lithium iron phosphate batteries mainly includes two parts: pretreatment and metal recycling. Among them, the metal recycling part is currently more researched. There are many methods to realize the recovery of positive active materials, but there is very little research on recycling pretreatment. . The traditional pretreatment method is to manually sort out the positive and negative electrodes of the battery after discharging and disassembling the battery pack, and then separate the positive and negative active materials from the current collector. This process is difficult to avoid manual participation, has low efficiency, poor safety, and is difficult to Achieve industrialization promotion. Therefore, finding a convenient and efficient method to dispose of used lithium-ion batteries is of great scientific significance and practical value.

Chinese patent application CN112961984A discloses a process for selective recovery of waste lithium-ion batteries to collect fluids. The waste lithium-ion batteries are discharged, dried, and incinerated, and then crushed, screened, and ball milled to obtain ball-milled materials. Take the ball-milled materials. After water washing and magnetic separation, a low magnetic current collector copper and aluminum mixture is obtained. The current collector copper and aluminum mixture is slurried and shaken to obtain current collector copper and current collector aluminum respectively. No new impurity ions are introduced during the complete separation process of this process, which greatly simplifies the subsequent impurity removal process, improves the purity of the copper and aluminum current collectors, and increases the sales value of the current collectors. However, the main purpose of this process is to obtain copper and aluminum current collectors, and it does not pay attention to the recovery of positive electrode black powder. It is first incinerated at high temperature and then screened with a large-aperture screen. The incineration process will make the copper current collector brittle, and then it will be crushed. A large amount of copper, aluminum, graphite and other impurities enter the cathode black powder, resulting in a high impurity content in the cathode black powder, which increases the pressure for subsequent recovery of valuable metals and reduces the recovery rate of copper and aluminum current collectors. In addition, the process of magnetic separation first and then shaker separation also has certain disadvantages, because the material contains The amount of magnetic material is very small, so very few magnetic materials are selected by magnetic separation first, leaving a large amount of material that has not been selected, which will increase unnecessary load and energy consumption of the magnetic separation section.

Contents of the invention

The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention proposes a method for recycling and pretreatment of used lithium-ion batteries. This method utilizes the inherent density, magnetism, volatilization temperature, toughness and other properties of the battery component materials, and uses the gravity selection and ignition process to realize the recycling of used lithium-ion batteries. Efficient and harmless recycling pretreatment.

According to one aspect of the present invention, a method for recycling and preprocessing waste lithium-ion batteries is proposed, which includes the following steps:

S1: Discharge the used lithium-ion batteries, remove the electrolyte, dry them, and crush the dried batteries to obtain crushed materials;

S2: The crushed material is sorted on a shaking table to obtain a first mixture containing steel slag, copper flakes, and graphite and a second mixture containing aluminum foil and black powder. The second mixture is roasted and screened under an inert atmosphere. , separate aluminum foil and black powder;

S3: The first mixture undergoes magnetic separation to separate steel slag and a third mixture containing copper flakes and graphite. The third mixture is roasted and screened in an inert atmosphere to separate copper flakes and graphite.

In some embodiments of the present invention, in step S1, the used lithium-ion battery is at least one of a lithium iron phosphate battery, a ternary lithium battery, a lithium manganate battery or a lithium cobalt oxide battery.

In some embodiments of the present invention, in step S1, the drying temperature is 80-200°C.

In some embodiments of the present invention, in step S1, the crushing process includes: first coarse crushing, and then fine crushing. After the fine crushing is completed, sieving is performed. The objects above the sieve are returned to the fine crushing process, and the objects under the sieve are The crushed materials enter the next step of shaking table sorting. Further, the screening is wet screening or dry screening.

In some embodiments of the present invention, the opening of the coarse fracture is 1-4cm; the opening of the fine fracture is 1-4mm. It should be noted that the coarse crushing opening and fine crushing opening refer to the diameter of the discharge port of the crusher.

In some embodiments of the present invention, in step S1, the particle size of the crushed material is ≤ 2 mm.

In some embodiments of the present invention, in step S2, the shaker is a hydraulic shaker with a transverse slope of 1.5°-5°, The stroke of the shaker is 15-35mm, and the stroke frequency is 100-150 times/min. The greater the bed slope of the shaker, the cleaner the separation of heavy substances will be, but the more heavy substances will be mixed into the light substances, so the bed slope must be strictly controlled.

In some embodiments of the present invention, in step S3, the magnetic field intensity of the magnetic separation is 600-1500Gs. Within this preferred range, the higher the magnetic field intensity, the better the steel slag separation effect and the higher the separation rate. Furthermore, the equipment used in the magnetic separation is a wet weak magnetic separator.

In some embodiments of the present invention, in step S2 and/or step S3, the roasting temperature is 300-800°C. Further, the roasting time is 30-240 minutes. The higher the baking temperature, the better the binder removal effect, and the higher the recovery rate of positive and negative electrode materials. However, the higher the degree of oxidation of copper sheets and aluminum foils, the higher the content of copper and aluminum impurities doped in positive and negative electrode materials, so it is necessary to Control the roasting temperature within an appropriate range.

In some embodiments of the present invention, in step S2 and/or step S3, the aperture of the screen used for screening is 0.025-0.074 mm.

In some embodiments of the present invention, in step S2 and/or step S3, the inert atmosphere is at least one of nitrogen, argon or helium.

In some embodiments of the present invention, the steam generated during the drying and roasting process enters the condensation system for recovery through pipelines.

According to a preferred embodiment of the present invention, it has at least the following beneficial effects:

1. The present invention first heats and dries the residual electrolyte and moisture, then crushes and screens the whole to control the particle size of the crushed material. The crushed material contains steel slag, copper sheets and graphite adhered to the copper sheets, aluminum foil and aluminum foil adhered to the aluminum foil. Black powder, then use a shaker to separate heavy substances and light substances, then use magnetic separation to separate steel slag, copper flakes and graphite, finally use roasting to burn off the binder, and use screening to separate copper flakes from graphite and aluminum foil. Separate from the positive black powder. Black powder is mainly a mixture of positive electrode powder, carbon powder and a small amount of graphite dropped during the crushing and screening process. During the subsequent wet leaching process of battery black powder, the positive electrode powder can be dissolved by acid, while graphite and carbon powder can be filtered as insoluble matter. If it falls off, it will have no impact on this process.

2. The present invention utilizes the difference in density of different materials, uses water as the medium, and uses a shaking table sorting process to simultaneously separate different materials. During the separation process, aluminum foil and black powder are relatively light and float on the top layer under the influence of water flow classification. The impact of the transverse water flow is greater, and the graphite and steel slag bonded to the copper sheet are subject to greater longitudinal impact. They can be intercepted at two different directions of the shaker to obtain light and heavy materials; then the strong magnetism of the steel slag and the non-magnetic nature of the copper sheet are used , after magnetic separation, steel slag and Separation of copper sheets.

3. The main purpose of the present invention is to obtain higher purity cathode black powder and at the same time achieve efficient recovery of copper, aluminum current collectors and other substances. Compared with the traditional process, the present invention cleverly places the roasting section at the end, which can avoid the copper current collector becoming brittle due to roasting in the shaking table section and being mixed into the black powder, resulting in excessive copper content in the black powder and a reduction in the copper recovery rate in the copper products. And other issues. Since the amounts of light and heavy materials in the crushed materials are similar, the present invention places the shaker before the magnetic separation, first the shaker selects half of the light materials, and the remaining half of the heavy materials are then subjected to magnetic separation, which greatly reduces the amount of materials entering the magnetic separation section. , reducing the load on the magnetic separation section and saving a lot of energy consumption. In addition, the traditional process generally leaves graphite in the positive electrode black powder. The graphite is insoluble in the wet process section and is left in the slag for recovery in the wet process section. The present invention can directly obtain most of the graphite products, and only a small amount of graphite is mixed in the positive electrode. Black powder is involved in subsequent leaching.

4. The present invention realizes the overall recycling of waste lithium-ion batteries through processes such as crushing, screening, shaking tables, magnetic separation, roasting, and secondary screening. The entire process can be completed mechanically without manual disassembly. The entire sorting process uses the inherent properties of materials for physical sorting. No chemical reagents are added during the whole process. It has almost no pollution to the environment and no harm to the human body. It is a green and efficient separation method.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and examples, wherein:

Figure 1 is a process flow diagram of the present invention.

Detailed ways

The concept of the present invention and the technical effects produced will be clearly and completely described below with reference to the embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without exerting creative efforts are all protection scope of the present invention.

Example 1

A method for recycling and preprocessing used lithium iron phosphate batteries. Refer to Figure 1. The specific process is:

Step 1: Put the lithium iron phosphate battery that has been fully discharged and drained of the electrolyte into an oven, set the temperature to 150°C, and dry for 3 hours to drain out the moisture and residual electrolyte. The generated gas enters the condensation system for recovery through the pipeline; the lithium iron phosphate battery The density of each material in the pool is: copper 8.9g/cm ³ , steel 7.85g/cm ³ , aluminum 2.7g/cm ³ , and lithium iron phosphate 1.523g/cm ³ ;

Step 2: Take out the dried batteries and put them into the jaw crusher for rough crushing. Adjust the opening of the jaw crusher to 2cm;

Step 3: Put the crushed materials into the roller crusher for fine crushing. The opening of the roller crusher is 2mm;

Step 4: Use a sieve with a mesh size of 2mm to screen the finely crushed materials. The material above the screen is returned to the double-roller crusher and continues to be crushed to less than 2mm. The material below the screen is processed in the next step;

Step 5: Set the shaker parameters to a transverse slope of 2.5°, a shaker stroke of 20cm, and a stroke rate of 140 times/min. The crushed and qualified materials are pulped to a concentration of 30%, and then slowly put into the shaker. After sorting by the shaker, A first mixture containing steel slag, copper flakes and graphite and a second mixture containing aluminum foil and black powder can be obtained;

Step 6: Set the magnetic field intensity of the magnetic drum to 800Gs. Pass the first mixture obtained in step 5 through the magnetic drum to separate out the steel slag and the third mixture containing copper flakes and graphite. The steel slag recovery rate is 97%;

Step 7: Put the third mixture obtained in Step 6 into a muffle furnace, set the temperature to 400°C, roast it for 60 minutes in a nitrogen atmosphere, and sieve it with a sieve with a mesh size of 0.038mm. The material on the sieve is copper sheet, and the material under the sieve is It is graphite slag, and the copper sheet recovery rate can reach 98%;

Step 8: Put the second mixture obtained in step 5 into a muffle furnace, set the temperature to 500°C, bake for 40 minutes in a nitrogen atmosphere, and sieve with a sieve with a mesh size of 0.038mm. The material above the sieve is aluminum foil, and the material under the sieve is For black powder, the recovery rate of aluminum foil is 97%, and the recovery rate of cathode powder in black powder is 95%.

Table 1 Element content of each product in Example 1

Example 2

A method for recycling and preprocessing used lithium iron phosphate batteries. The specific process is:

Step 1: Put the lithium iron phosphate battery that has been fully discharged and drained of the electrolyte into an oven, set the temperature to 180°C, and dry for 2 hours to drain out the moisture and residual electrolyte. The generated gas enters the condensation system for recovery through the pipeline;

Step 2: Take out the dried batteries and put them into the jaw crusher for rough crushing. Adjust the opening of the jaw crusher to 2cm;

Step 3: Put the crushed materials into the roller crusher for fine crushing. The opening of the roller crusher is 2mm;

Step 4: Use a sieve with a mesh size of 2mm to screen the finely crushed materials. The material above the screen is returned to the double-roller crusher and continues to be crushed to less than 2mm. The material below the screen is processed in the next step;

Step 5: Set the shaker parameters to a transverse slope of 3.5°, a shaker stroke of 18cm, and a stroke rate of 140 times/min. The crushed and qualified materials are pulped to a concentration of 30%, and then slowly put into the shaker. After sorting by the shaker, A first mixture containing steel slag, copper flakes and graphite and a second mixture containing aluminum foil and black powder can be obtained;

Step 6: Set the magnetic field intensity of the magnetic drum to 800Gs. Pass the first mixture obtained in step 5 through the magnetic drum to separate out the steel slag and the third mixture containing copper flakes and graphite. The steel slag recovery rate is 97%;

Step 7: Put the third mixture obtained in step 6 into a muffle furnace, set the temperature to 500°C, roast it for 40 minutes in a nitrogen atmosphere, and sieve it with a sieve with a mesh size of 0.038mm. The material on the sieve is copper sheet, and the material under the sieve is It is graphite slag, and the copper sheet recovery rate is 97.5%;

Step 8: Put the second mixture obtained in step 5 into a muffle furnace, set the temperature to 600°C, bake for 40 minutes in a nitrogen atmosphere, and sieve with a sieve with a mesh size of 0.038mm. The material above the sieve is aluminum foil, and the material under the sieve is The recovery rate of black powder and aluminum foil is 98%, and the recovery rate of cathode powder in black powder is 94.5%.

Table 2 Element content of each product in Example 2

Example 3

A method for recycling and preprocessing used lithium iron phosphate batteries. The specific process is:

Step 1: Put the lithium iron phosphate battery that has been fully discharged and drained of the electrolyte into an oven, set the temperature to 180°C, and dry for 2 hours to drain out the moisture and residual electrolyte. The generated gas enters the condensation system for recovery through the pipeline;

Step 2: Take out the dried batteries and put them into the jaw crusher for rough crushing. Adjust the opening of the jaw crusher to 2cm;

Step 3: Put the crushed materials into the roller crusher for fine crushing. The opening of the roller crusher is 2mm;

Step 4: Use a sieve with a mesh size of 2mm to screen the finely crushed materials. The material above the screen is returned to the double-roller crusher and continues to be crushed to less than 2mm. The material below the screen is processed in the next step;

Step 5: Set the shaker parameters to a transverse slope of 3.5°, a shaker stroke of 23cm, and a stroke rate of 140 times/min. The crushed and qualified materials are pulped to a concentration of 30%, and then slowly put into the shaker. After sorting by the shaker, A first mixture containing steel slag, copper flakes and graphite and a second mixture containing aluminum foil and black powder can be obtained;

Step 6: Set the magnetic field intensity of the magnetic drum to 1500Gs. Pass the first mixture obtained in step 5 through the magnetic drum to separate out the steel slag and the third mixture containing copper flakes and graphite. The steel slag recovery rate is 98%;

Step 7: Put the third mixture obtained in step 6 into a muffle furnace, set the temperature to 500°C, roast it for 40 minutes in a nitrogen atmosphere, and sieve it with a sieve with a mesh size of 0.038mm. The material on the sieve is copper sheet, and the material under the sieve is It is graphite slag, and the copper sheet recovery rate is 97%;

Step 8: Put the second mixture obtained in step 5 into a muffle furnace, set the temperature to 600°C, bake for 120 minutes in a nitrogen atmosphere, and sieve it with a sieve with a mesh size of 0.038mm. The material above the sieve is aluminum foil, and the material under the sieve is The recovery rate of black powder and aluminum foil is 96.5%, and the recovery rate of cathode powder in black powder is 96%.

Table 3 Element content of each product in Example 3

The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those of ordinary skill in the art, various modifications can be made without departing from the purpose of the present invention. Variety. In addition, the embodiments of the present invention and the features in the embodiments may be combined with each other without conflict.

Claims (10)

A method for recycling and preprocessing old lithium-ion batteries, which is characterized by including the following steps: S1: Discharge the used lithium-ion batteries, remove the electrolyte, dry them, and crush the dried batteries to obtain crushed materials; S2: The crushed material is sorted on a shaking table to obtain a first mixture containing steel slag, copper flakes, and graphite and a second mixture containing aluminum foil and black powder. The second mixture is roasted and screened under an inert atmosphere. , separate aluminum foil and black powder; S3: The first mixture undergoes magnetic separation to separate steel slag and a third mixture containing copper flakes and graphite. The third mixture is roasted and screened in an inert atmosphere to separate copper flakes and graphite. The method according to claim 1, characterized in that in step S1, the drying temperature is 80-200°C. The method according to claim 1, characterized in that in step S1, the crushing process includes: first coarse crushing, then fine crushing, screening after the fine crushing is completed, and the objects on the sieve are returned to the fine crushing process, and then screened The lower material is the crushed material and enters the next step of shaking table sorting. The method according to claim 3, characterized in that the opening of the coarse fracture is 1-4cm; the opening of the fine fracture is 1-4mm. The method according to claim 1, characterized in that in step S1, the particle size of the crushed material is ≤ 2 mm. The method according to claim 1, characterized in that in step S2, the shaker is a hydraulic shaker, the transverse slope is 1.5°-5°, the stroke of the shaker is 15-35mm, and the number of strokes is 100-150 times /min. The method according to claim 1, characterized in that in step S3, the magnetic field intensity of the magnetic separation is 600-1500Gs. The method according to claim 1, characterized in that in step S2 and/or step S3, the roasting temperature is 300-800°C. The method according to claim 1, characterized in that in step S2 and/or step S3, the aperture of the screen used for screening is 0.025-0.074mm. The method according to claim 1, characterized in that the steam generated during the drying and roasting process enters the condensation system for recovery through pipelines.