Method for separating and recycling valuable metal from waste lithium ion battery positive electrode material

Abstract

The invention belongs to the technical field of lithium ion battery resource recovery, and particularly relates to a method for separating and recovering valuable metals from a waste lithium ion battery positive electrode material, which comprises the following steps: pretreating a waste lithium ion battery, separating the positive electrode material, and post-treating the positive electrode material to obtain a post-treated positive electrode material; the method comprises the steps that bagasse is pretreated, then a citric acid solution is added into the pretreated bagasse, heating reaction is conducted, and bagasse-citric acid leaching liquid is obtained; putting the post-treated positive electrode material into the bagasse-citric acid leaching solution for leaching to obtain a leaching solution containing valuable metals; according to the method, the valuable metal in the leaching solution containing the valuable metal is leached through a chemical precipitation method, the waste lithium ion battery is recycled through the bagasse, the recycling cost can be reduced, the recycling technology can be optimized, household garbage can be utilized, resource waste is reduced, and meanwhile the treatment method of the bagasse is widened.

Description

Technical Field

[0001] The invention belongs to the technical field of lithium ion battery resource recovery, and in particular relates to a method for separating and recovering valuable metals from waste lithium ion battery positive electrode materials. Background Art

[0002] Waste lithium-ion batteries have outstanding resource characteristics. They are rich in metal elements such as lithium, cobalt, nickel, manganese and copper, and have become important valuable metal deposits. The content of these metals in the positive electrode material can account for 50% of the total mass of the entire battery cell, especially Li (1.9%), Ni (12.1%), Co (2.3%), Cu (13.3%) and other elements, which are much higher than metal ores. At present, the recycling of waste lithium batteries is still in the research stage, and an integrated industrial chain has not yet been formed. The recycling quantity and scale are very limited. A large number of waste lithium batteries are still in an unrecycled state and are idle in garbage recycling sites or waste recycling sites. If they are piled up for a long time, they will cause irreversible damage to the environment and human health.

[0003] At present, the recycling and utilization of waste lithium-ion batteries can be roughly divided into four stages, including recycling, pretreatment, separation of active substances and reuse of battery active materials. Combined with the current status of resource utilization and extraction by professional recycling companies, there are two main technologies currently used, namely dry method and wet method.

[0004] From the existing research reports, hydrometallurgy-chemical precipitation method has become a research hotspot. In the process of hydrometallurgy, the reducing agents used are mostly inorganic reducing agents, especially hydrogen peroxide, while there are fewer studies on organic reducing agents and biomass reducing agents. At present, the research on biomass reducing agents has become a trend. The use of biomass reducing agents to recycle waste lithium batteries not only provides new data for biomass reducing agents, but also realizes the reuse of waste resources, reduces the waste of valuable metal resources, and improves the reuse rate of waste. The existing technology uses corn platycodon as a reducing agent to separate and recover valuable metals. Although the leaching rate of lithium using corn stalks is higher, the leaching rate of cobalt is lower, and the price of cobalt is much more expensive than lithium, and cobalt is more toxic. Summary of the invention

[0005] In view of the deficiencies of the above-mentioned prior art, the purpose of the present invention is to provide a method for separating and recovering valuable metals from the positive electrode materials of discarded lithium-ion batteries. The preparation method of the present invention uses bagasse to recycle waste lithium-ion batteries, which can not only reduce the recycling cost and optimize the recycling technology, but also utilize domestic waste, reduce resource waste, and broaden the treatment methods of bagasse.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials comprises the following steps:

[0008] The waste lithium-ion batteries are pre-processed to separate the positive electrode materials, and the positive electrode materials are post-processed to obtain the post-processed positive electrode materials.

[0009] The sugarcane bagasse is pretreated, and then a citric acid solution is added to the pretreated sugarcane bagasse, and the bagasse is soaked at a constant temperature to obtain a sugarcane bagasse-citric acid extract.

[0010] The post-treated positive electrode material is placed in the bagasse-citric acid leaching solution, and ultrasonic heating reaction is performed. The cellulose and hemicellulose in the bagasse are hydrolyzed in an acidic environment to generate reducing sugars, thereby enhancing the reducing property of the leaching system, leaching valuable metals, and obtaining a leaching solution containing valuable metals.

[0011] The valuable metals in the leaching solution containing the valuable metals are precipitated by chemical precipitation to achieve the recovery of the valuable metals.

[0012] The present invention uses bagasse to recycle waste lithium-ion batteries. Bagasse contains more carbohydrates, such as cellulose and hemicellulose. Under acidic conditions, cellulose and hemicellulose will be hydrolyzed to generate reducing sugars, which enhances the reducing property of the leaching system and is beneficial to improving the leaching rate of valuable metals. The present invention uses bagasse as a reducing agent to separate and recover valuable metals, and the leaching rate of cobalt is relatively high.

[0013] In a preferred embodiment of the present invention, the concentration of the citric acid solution is 2.0 mol / L to 3.0 mol / L.

[0014] In a preferred embodiment of the present invention, the mass fraction of bagasse in the bagasse-citric acid leaching solution is 0.2% to 1.0%.

[0015] In a preferred embodiment of the present invention, the volume ratio of the post-treated positive electrode material mass to the citric acid solution is 25 g to 30 g:1L.

[0016] In a preferred embodiment of the present invention, the heating reaction temperature is 80°C to 90°C.

[0017] In a preferred embodiment of the present invention, the heating reaction time is 5 h to 6.5 h.

[0018] In a preferred embodiment of the present invention, the valuable metal is cobalt, lithium, nickel, manganese or copper.

[0019] In a preferred embodiment of the present invention, the pretreatment method of waste lithium-ion batteries is: using sodium hydroxide solution to discharge the waste lithium-ion batteries, and performing a voltage test, when the voltage is lower than 1.5V, disassembling and separating to obtain the positive electrode material.

[0020] Bagasse has huge production, concentrated raw materials, is cheap and easy to obtain, and is renewable. It is an environmentally friendly and sustainable biomass resource. However, the current utilization of bagasse is mainly used for pulping and papermaking, producing artificial boards, and producing ethanol. These treatment methods not only have low utilization rates, cause resource waste, but also increase environmental pressure. Therefore, the present invention uses bagasse to recycle waste lithium-ion batteries to improve the leaching rate of valuable metals.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The method for separating and recovering valuable metals from positive electrode materials of waste lithium ion batteries of the present invention comprises the following steps: pre-treating waste lithium ion batteries to separate positive electrode materials, and post-treating the positive electrode materials to obtain post-treated positive electrode materials; pre-treating bagasse, and then adding citric acid solution to the pre-treated bagasse for constant temperature immersion to obtain bagasse-citric acid leaching solution; placing the post-treated positive electrode materials into the bagasse-citric acid leaching solution, performing ultrasonic heating reaction, leaching valuable metals, and obtaining a leaching solution containing valuable metals; and precipitating the valuable metals in the leaching solution containing valuable metals by chemical precipitation to achieve the recovery of valuable metals. The present invention adopts bagasse to recover waste lithium ion batteries. Bagasse contains more carbohydrates, such as cellulose and hemicellulose. Under acidic conditions, cellulose and hemicellulose are hydrolyzed to generate reducing sugars, thereby enhancing the reducing property of the leaching system and facilitating the improvement of the leaching rate of valuable metals. The present invention uses bagasse as a reducing agent to separate and recover valuable metals, and the leaching rate of cobalt is higher.

[0023] 2. The present invention uses bagasse biomass reducing agent to recycle waste lithium-ion batteries, which can not only realize the reuse of waste resources, but also reduce the recycling cost of lithium-ion batteries, optimize recycling technology, and utilize domestic waste to reduce resource waste, while broadening the treatment method of bagasse. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the basic process of recovering valuable metals from lithium-ion battery positive electrode materials by leaching biomass materials.

[0025] Figure 2 It is the technical roadmap of the present invention.

[0026] Figure 3 The figure shows the influence of different citric acid concentrations on the metal leaching rate in the lithium cobalt oxide battery of the present invention.

[0027] Figure 4 The present invention shows the influence of different reaction temperatures on the metal leaching rate in the lithium cobalt oxide battery.

[0028] Figure 5The figure shows the influence of different reaction times on the metal leaching rate in the lithium cobalt oxide battery of the present invention.

[0029] Figure 6 The present invention shows the influence of different bagasse mass fractions on the metal leaching rate in lithium cobalt oxide batteries.

[0030] Figure 7 The present invention shows the influence of different solid-liquid ratios on the metal leaching rate in the lithium cobalt oxide battery. DETAILED DESCRIPTION

[0031] The following is a detailed description of the technical solutions in the embodiments of the present invention in combination with the preferred embodiments and the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] It should be noted that all professional terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specifically stated, various raw materials, reagents, instruments and equipment used in the following embodiments of the present invention can be purchased from the market or prepared by existing methods.

[0033] There are a huge number of waste lithium-ion batteries, and a large number of them are idle in garbage recycling plants or waste recycling plants. Long-term stacking and placement will cause irreversible damage to the environment and human health. At the same time, the positive electrode materials of lithium-ion batteries are rich in metal elements such as lithium, cobalt, nickel, manganese and copper. These metal elements are non-renewable and have a very high recycling value; sugarcane bagasse has a huge output, concentrated raw materials, is cheap and easy to obtain and renewable, and is an environmentally sustainable biomass resource. However, the current utilization of sugarcane bagasse is mainly used for pulping and papermaking, producing artificial boards and producing ethanol, etc. These treatment methods not only have low utilization rates, cause waste of resources, but also increase environmental pressure. In existing studies, the reducing agents used to leaching valuable metals in waste lithium-ion batteries are mostly inorganic or organic reducing agents, and there is less research on biomass reducing agents. Using sugarcane bagasse biomass reducing agents to recycle waste lithium batteries can not only realize the reuse of waste resources, but also reduce the recycling cost of lithium-ion batteries. The test methods not mentioned in the present invention all use existing technologies.

[0034] Example 1

[0035] A method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials comprises the following steps:

[0036] (1) Pretreatment of waste lithium-ion batteries

[0037] The pretreatment of waste lithium-ion batteries mainly includes the discharge of waste lithium-ion batteries and the separation of current collectors. The waste lithium-ion batteries are discharged using a conductive salt solution. The waste lithium-ion batteries are first soaked in a sodium hydroxide solution, and the voltage is tested every 1 hour to determine whether they meet the standard for manual disassembly. When the voltage is below 1.5V, manual disassembly can be performed; the metal shell is cut 0.5cm away from the electrode to preserve the internal electrolyte for subsequent treatment, and the packaging shell and packaging skin are recovered. Then all the electrodes are taken out and separated to obtain the positive electrode material, and the positive electrode material is cut into 2cm×2cm fragments for standby use. In the present invention, lithium cobalt oxide positive electrode material is taken as an example.

[0038] Conductive salts are often saturated sodium chloride solutions. Although saturated sodium chloride solutions can quickly discharge lithium-ion batteries, they will corrode electrode sheets, causing toxic electrolyte leakage. At the same time, the discharge speed is too fast, and the risk of explosion is greater. Therefore, the present invention selects sodium hydroxide as the conductive salt when pretreating waste lithium-ion batteries.

[0039] The lithium cobalt oxide positive electrode material was post-processed: the lithium cobalt oxide positive electrode material was placed in a vacuum drying oven at 120°C, dried for 24 hours, and then sieved through a standard sieve of 180 meshes. The sieved lithium cobalt oxide positive electrode material was collected and fully ground for 30 minutes, and then placed in a muffle furnace, calcined at 900°C for 6 hours, and then taken out. Impurities such as the electrolyte solution and the binder were removed by high temperature, and finally ground again for 30 minutes to obtain the lithium cobalt oxide positive electrode material used for the leaching study.

[0040] (2) Leaching of valuable metals by citric acid-bagasse leaching system

[0041] The bagasse was pre-treated by washing and vacuum drying, crushed by a multifunctional pulverizer, sieved by a 100-mesh standard test sieve, and then weighed into a 250-mL conical flask filled with a 2.5 mol / L citric acid solution, wherein the mass fraction of the bagasse was 0.4%. The conical flask was placed in a magnetic stirrer and immersed in a constant temperature 80°C water bath for 3 h to obtain a citric acid-bagasse extract.

[0042] (3) placing the lithium cobalt oxide positive electrode material obtained in step (1) into a citric acid-bagasse leachate, wherein the solid-liquid ratio is 25 g / L, and the solid-liquid ratio refers to the volume ratio of the mass of the post-treated positive electrode material to the citric acid solution, and subjecting the material to ultrasonic treatment at a constant temperature of 80° C. for 6 h to leach out the valuable metals and obtain a leachate containing the valuable metals.

[0043] (4) Recovery of valuable metals by chemical precipitation

[0044] Add an appropriate amount of ammonium oxalate solution to the leachate containing valuable metals, heat in a water bath and stir, and let it stand for 2 hours after stirring. It can be clearly seen that there is precipitation at the bottom of the leachate, and the color of the leachate changes from pink to colorless. Then vacuum filter and dry in a vacuum drying oven to obtain the cobalt precipitate CoC 2 O 4 ·2H 2 O and lithium precipitate lithium carbonate, then adjust the filtrate pH to 7.0 by adding saturated sodium carbonate solution, and adjust the molar ratio of cobalt ions to carbonate to 1.15:1, the reaction temperature is 50 ° C, the reaction time is 120 min, filter while hot to obtain lithium carbonate, dry and heat cobalt oxalate and lithium carbonate, calculate the recovery rate of cobalt and lithium, the basic process of valuable metal recovery is as follows Figure 1 shown.

[0045] Example 2

[0046] A method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials comprises the following steps:

[0047] (1) The bagasse was pre-treated by washing and vacuum drying, crushed by a multifunctional crusher, sieved by a standard test sieve, and then weighed into a 250 mL conical flask containing a 3.0 mol / L citric acid solution, wherein the mass fraction of the bagasse was 0.4%. The conical flask was placed in a magnetic stirrer and immersed in a constant temperature 80° C. water bath for 3 h to obtain a citric acid-bagasse extract.

[0048] (2) The lithium cobalt oxide positive electrode material is placed in a citric acid-bagasse leaching solution, wherein the solid-liquid ratio is 25 g / L, and constant temperature ultrasound is applied for 6 hours to leach the valuable metals to obtain a leaching solution containing the valuable metals.

[0049] (3) The valuable metals in the leaching solution containing the valuable metals are precipitated by chemical precipitation method, and the recovery rate of the valuable metals is tested.

[0050] Example 3

[0051] A method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials comprises the following steps:

[0052] (1) The sugarcane bagasse was pre-treated by washing and vacuum drying, crushed by a multifunctional crusher, sieved by a standard test sieve, and then weighed into a 250 mL conical flask containing a 2.0 mol / L citric acid solution, wherein the mass fraction of the sugarcane bagasse was 0.4%. The conical flask was placed in a magnetic stirrer and immersed in a constant temperature 80° C. water bath for 3 h to obtain a citric acid-sugarcane bagasse extract.

[0053] (2) The lithium cobalt oxide positive electrode material is placed in a citric acid-bagasse leachate, wherein the solid-liquid ratio is 25 g / L, and the valuable metals are leached out by ultrasonic treatment at a constant temperature of 80° C. to obtain a leachate containing the valuable metals.

[0054] (3) Precipitating the valuable metals in the leaching solution containing the valuable metals by chemical precipitation method, and testing the recovery rate of the valuable metals.

[0055] Example 4

[0056] A method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials comprises the following steps:

[0057] (1) The sugarcane bagasse was pre-treated by washing and vacuum drying, crushed by a multifunctional crusher, sieved by a standard test sieve, and then weighed into a 250 mL conical flask containing a 2.5 mol / L citric acid solution, wherein the mass fraction of the sugarcane bagasse was 0.4%, and the conical flask was placed in a magnetic stirrer in a constant temperature 80° C. water bath for leaching to obtain a citric acid-sugarcane bagasse extract.

[0058] (2) The lithium cobalt oxide positive electrode material is placed in a citric acid-bagasse leachate, wherein the solid-liquid ratio is 25 g / L, and the valuable metals are leached out by ultrasonic reaction at a constant temperature of 90° C. to obtain a leachate containing valuable metals.

[0059] (3) Precipitating the valuable metals in the leaching solution containing the valuable metals by chemical precipitation method, and testing the recovery rate of the valuable metals.

[0060] Example 5

[0061] A method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials comprises the following steps:

[0062] (1) The bagasse was pre-treated by washing and vacuum drying, crushed by a multifunctional crusher, sieved by a standard test sieve, and then weighed into a 250 mL conical flask containing a 2.5 mol / L citric acid solution, wherein the mass fraction of the bagasse was 0.6%. The conical flask was placed in a magnetic stirrer and immersed in a constant temperature 80° C. water bath for 3 h to obtain a citric acid-bagasse extract.

[0063] (2) The lithium cobalt oxide positive electrode material is placed in a citric acid-bagasse leachate, wherein the solid-liquid ratio is 25 g / L, and the valuable metals are leached out by ultrasonic treatment at a constant temperature of 80° C. to obtain a leachate containing the valuable metals.

[0064] (3) Precipitating the valuable metals in the leaching solution containing the valuable metals by chemical precipitation method, and testing the recovery rate of the valuable metals.

[0065] Example 6

[0066] A method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials comprises the following steps:

[0067] (1) The bagasse was pre-treated by washing and vacuum drying, crushed by a multifunctional crusher, sieved by a standard test sieve, and then weighed into a 250 mL conical flask containing a 2.5 mol / L citric acid solution, wherein the mass fraction of the bagasse was 0.8%, and the conical flask was placed in a magnetic stirrer and immersed in a constant temperature 80° C. water bath for 3 h to obtain a citric acid-bagasse extract.

[0068] (2) The lithium cobalt oxide positive electrode material is placed in a citric acid-bagasse leachate, wherein the solid-liquid ratio is 25 g / L, and the valuable metals are leached out by ultrasonic treatment at a constant temperature of 80° C. to obtain a leachate containing the valuable metals.

[0069] (3) Leaching the valuable metals from the leaching solution containing the valuable metals by a chemical precipitation method to obtain the valuable metals, and testing the recovery rate of the valuable metals.

[0070] Example 7

[0071] A method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials comprises the following steps:

[0072] (1) The bagasse was pre-treated by washing and vacuum drying, crushed by a multifunctional crusher, sieved by a standard test sieve, and then weighed into a 250 mL conical flask containing a 2.5 mol / L citric acid solution, wherein the mass fraction of the bagasse was 1.0%, and the conical flask was placed in a magnetic stirrer and immersed in a constant temperature 80° C. water bath for 3 h to obtain a citric acid-bagasse extract.

[0073] (2) The lithium cobalt oxide positive electrode material is placed in a citric acid-bagasse leachate, wherein the solid-liquid ratio is 25 g / L, and the valuable metals are leached out by ultrasonic treatment at a constant temperature of 80° C. to obtain a leachate containing the valuable metals.

[0074] (3) Precipitating the valuable metals in the leaching solution containing the valuable metals by chemical precipitation method, and testing the recovery rate of the valuable metals.

[0075] Example 8

[0076] A method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials comprises the following steps:

[0077] (1) The bagasse was pre-treated by washing and vacuum drying, crushed by a multifunctional crusher, sieved by a standard test sieve, and then weighed into a 250 mL conical flask containing a 2.5 mol / L citric acid solution, wherein the mass fraction of the bagasse was 0.2%, and the conical flask was placed in a magnetic stirrer and immersed in a constant temperature 80° C. water bath for 3 h to obtain a citric acid-bagasse extract.

[0078] (2) The lithium cobalt oxide positive electrode material is placed in a citric acid-bagasse leachate, wherein the solid-liquid ratio is 25 g / L, and the valuable metals are leached out by ultrasonic treatment at a constant temperature of 80° C. to obtain a leachate containing the valuable metals.

[0079] (3) Precipitating the valuable metals in the leaching solution containing the valuable metals by chemical precipitation method, and testing the recovery rate of the valuable metals.

[0080] Example 9

[0081] A method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials comprises the following steps:

[0082] (1) The sugarcane bagasse was pre-treated by washing and vacuum drying, crushed by a multifunctional crusher, sieved by a standard test sieve, and then weighed into a 250 mL conical flask containing a 2.5 mol / L citric acid solution, wherein the mass fraction of the sugarcane bagasse was 0.4%, and the conical flask was placed in a magnetic stirrer in a constant temperature 80° C. water bath for leaching to obtain a citric acid-sugarcane bagasse extract.

[0083] (2) The lithium cobalt oxide positive electrode material is placed in a citric acid-bagasse leachate, wherein the solid-liquid ratio is 25 g / L, and the valuable metals are leached out by ultrasonic treatment at a constant temperature of 80° C. to obtain a leachate containing the valuable metals.

[0084] (3) Precipitating the valuable metals in the leaching solution containing the valuable metals by chemical precipitation method, and testing the recovery rate of the valuable metals.

[0085] Example 10

[0086] A method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials comprises the following steps:

[0087] (1) The sugarcane bagasse was pre-treated by washing and vacuum drying, crushed by a multifunctional crusher, sieved by a standard test sieve, and then weighed into a 250 mL conical flask containing a 2.5 mol / L citric acid solution, wherein the mass fraction of the sugarcane bagasse was 0.4%. The conical flask was placed in a magnetic stirrer and immersed in a constant temperature 80° C. water bath for 3 h to obtain a citric acid-sugarcane bagasse extract.

[0088] (2) The lithium cobalt oxide positive electrode material is placed in a citric acid-bagasse leachate, wherein the solid-liquid ratio is 30 g / L, and the valuable metals are leached out by ultrasonic treatment at a constant temperature of 80° C. to obtain a leachate containing the valuable metals.

[0089] (3) Precipitating the valuable metals in the leaching solution containing the valuable metals by chemical precipitation method, and testing the recovery rate of the valuable metals.

[0090] Embodiment 11

[0091] A method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials comprises the following steps:

[0092] (1) The sugarcane bagasse was pre-treated by washing and vacuum drying, crushed by a multifunctional crusher, sieved by a standard test sieve, and then weighed into a 250 mL conical flask containing a 2.5 mol / L citric acid solution, wherein the mass fraction of the sugarcane bagasse was 0.4%. The conical flask was placed in a magnetic stirrer and immersed in a constant temperature 80° C. water bath for 3 h to obtain a citric acid-sugarcane bagasse extract.

[0093] (2) The lithium cobalt oxide positive electrode material is placed in a citric acid-bagasse leachate, wherein the solid-liquid ratio is 20 g / L, and the valuable metals are leached out by ultrasonic treatment at a constant temperature of 80° C. to obtain a leachate containing the valuable metals.

[0094] (3) Precipitating the valuable metals in the leaching solution containing the valuable metals by chemical precipitation method, and testing the recovery rate of the valuable metals.

[0095] Example 12

[0096] A method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials comprises the following steps:

[0097] (1) The sugarcane bagasse was pre-treated by washing and vacuum drying, crushed by a multifunctional crusher, sieved by a standard test sieve, and then weighed into a 250 mL conical flask containing a 2.5 mol / L citric acid solution, wherein the mass fraction of the sugarcane bagasse was 0.4%. The conical flask was placed in a magnetic stirrer and immersed in a constant temperature 80° C. water bath for 3 h to obtain a citric acid-sugarcane bagasse extract.

[0098] (2) The lithium cobalt oxide positive electrode material is placed in a citric acid-bagasse leachate, wherein the solid-liquid ratio is 25 g / L, and a constant temperature ultrasonic reaction is performed for 5 hours to leach the valuable metals and obtain a leachate containing the valuable metals.

[0099] (3) The valuable metals in the leaching solution containing the valuable metals are precipitated by chemical precipitation method, and the recovery rate of the valuable metals is tested.

[0100] Embodiment 13

[0101] A method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials comprises the following steps:

[0102] (1) The sugarcane bagasse was pre-treated by washing and vacuum drying, crushed by a multifunctional crusher, sieved by a standard test sieve, and then weighed into a 250 mL conical flask containing a 2.5 mol / L citric acid solution, wherein the mass fraction of the sugarcane bagasse was 0.4%. The conical flask was placed in a magnetic stirrer and immersed in a constant temperature 80° C. water bath for 3 h to obtain a citric acid-sugarcane bagasse extract.

[0103] (2) The lithium cobalt oxide positive electrode material is placed in a citric acid-bagasse leaching solution, wherein the solid-liquid ratio is 25 g / L, and constant temperature ultrasound is applied for 6.5 hours to leach out the valuable metals to obtain a leaching solution containing the valuable metals.

[0104] (3) The valuable metals in the leaching solution containing the valuable metals are precipitated by chemical precipitation method, and the recovery rate of the valuable metals is tested.

[0105] Comparative Example 1

[0106] A method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials comprises the following steps:

[0107] (1) The lithium cobalt oxide positive electrode material is placed in a citric acid leaching solution to leach valuable metals, thereby obtaining a leaching solution containing valuable metals.

[0108] (2) The valuable metals in the leaching solution containing the valuable metals are precipitated by chemical precipitation to obtain a valuable metal precipitate, and the recovery rate of the valuable metals is tested. The testing method is the same as that in Example 1.

[0109] Comparative Example 2

[0110] A method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials comprises the following steps:

[0111] (1) The bagasse was pre-treated by washing and vacuum drying, crushed by a multifunctional crusher, sieved by a standard test sieve, and then weighed into a 250 mL conical flask containing a 1.0 mol / L citric acid solution, wherein the mass fraction of the bagasse was 0.4%. The conical flask was placed in a magnetic stirrer and immersed in a constant temperature 80° C. water bath for 3 h to obtain a citric acid-bagasse extract.

[0112] (2) The lithium cobalt oxide positive electrode material is placed in a citric acid-bagasse leachate, wherein the solid-liquid ratio is 25 g / L, and the valuable metals are leached out by ultrasonic treatment at a constant temperature of 80° C. to obtain a leachate containing the valuable metals.

[0113] (3) Precipitating the valuable metals in the leaching solution containing the valuable metals by chemical precipitation method, and testing the recovery rate of the valuable metals.

[0114] Comparative Example 3

[0115] A method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials comprises the following steps:

[0116] (1) The bagasse was pre-treated by washing and vacuum drying, crushed by a multifunctional crusher, sieved by a standard test sieve, and then weighed into a 250 mL conical flask containing a 1.5 mol / L citric acid solution, wherein the mass fraction of the bagasse was 0.4%. The conical flask was placed in a magnetic stirrer and immersed in a constant temperature water bath of 80° C. for 3 h to obtain a citric acid-bagasse extract.

[0117] (2) The lithium cobalt oxide positive electrode material is placed in a citric acid-bagasse leachate, wherein the solid-liquid ratio is 25 g / L, and the valuable metals are leached out by ultrasonic treatment at a constant temperature of 80° C. to obtain a leachate containing the valuable metals.

[0118] (3) Precipitating the valuable metals in the leaching solution containing the valuable metals by chemical precipitation method, and testing the recovery rate of the valuable metals.

[0119] Comparative Example 4

[0120] A method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials comprises the following steps:

[0121] (1) The sugarcane bagasse was pre-treated by washing and vacuum drying, crushed by a multifunctional crusher, sieved by a standard test sieve, and then weighed into a 250 mL conical flask containing a 2.5 mol / L citric acid solution, wherein the mass fraction of the sugarcane bagasse was 0.4%. The conical flask was placed in a magnetic stirrer and immersed in a constant temperature 80° C. water bath for 3 h to obtain a citric acid-sugarcane bagasse extract.

[0122] (2) The lithium cobalt oxide positive electrode material is placed in a citric acid-bagasse leachate, wherein the solid-liquid ratio is 25 g / L, and the valuable metals are leached out by ultrasonic treatment at a constant temperature of 50° C. to obtain a leachate containing the valuable metals.

[0123] (3) Leaching the valuable metals from the leaching solution containing the valuable metals by a chemical precipitation method to obtain the valuable metals, and testing the recovery rate of the valuable metals.

[0124] Comparative Example 5

[0125] A method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials comprises the following steps:

[0126] (1) The sugarcane bagasse was pre-treated by washing and vacuum drying, crushed by a multifunctional crusher, sieved by a standard test sieve, and then weighed into a 250 mL conical flask containing a 2.5 mol / L citric acid solution, wherein the mass fraction of the sugarcane bagasse was 0.4%. The conical flask was placed in a magnetic stirrer and immersed in a constant temperature 80° C. water bath for 3 h to obtain a citric acid-sugarcane bagasse extract.

[0127] (2) The lithium cobalt oxide positive electrode material is placed in a citric acid-bagasse leachate, wherein the solid-liquid ratio is 25 g / L, and the valuable metals are leached out by ultrasonic treatment at a constant temperature of 60° C. to obtain a leachate containing the valuable metals.

[0128] (3) Precipitating the valuable metals in the leaching solution containing the valuable metals by chemical precipitation method, and testing the recovery rate of the valuable metals.

[0129] Comparative Example 6

[0130] A method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials comprises the following steps:

[0131] (1) The sugarcane bagasse was pre-treated by washing and vacuum drying, crushed by a multifunctional crusher, sieved by a standard test sieve, and then weighed into a 250 mL conical flask containing a 2.5 mol / L citric acid solution, wherein the mass fraction of the sugarcane bagasse was 0.4%. The conical flask was placed in a magnetic stirrer and immersed in a constant temperature 80° C. water bath for 3 h to obtain a citric acid-sugarcane bagasse extract.

[0132] (2) The lithium cobalt oxide positive electrode material is placed in a citric acid-bagasse leachate, wherein the solid-liquid ratio is 25 g / L, and the valuable metals are leached out by ultrasonic treatment at a constant temperature of 70° C. to obtain a leachate containing the valuable metals.

[0133] (3) Precipitating the valuable metals in the leaching solution containing the valuable metals by chemical precipitation method, and testing the recovery rate of the valuable metals.

[0134] Comparative Example 7

[0135] A method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials comprises the following steps:

[0136] (1) The sugarcane bagasse was pre-treated by washing and vacuum drying, crushed by a multifunctional crusher, sieved by a standard test sieve, and then weighed into a 250 mL conical flask containing a 2.5 mol / L citric acid solution, wherein the mass fraction of the sugarcane bagasse was 0.4%. The conical flask was placed in a magnetic stirrer and immersed in a constant temperature 80° C. water bath for 3 h to obtain a citric acid-sugarcane bagasse extract.

[0137] (2) The lithium cobalt oxide positive electrode material is placed in a citric acid-bagasse leachate, wherein the solid-liquid ratio is 10 g / L, and the valuable metals are leached out by ultrasonic treatment at a constant temperature of 80° C. to obtain a leachate containing the valuable metals.

[0138] (3) Precipitating the valuable metals in the leaching solution containing the valuable metals by chemical precipitation method, and testing the recovery rate of the valuable metals.

[0139] Comparative Example 8

[0140] A method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials comprises the following steps:

[0141] (1) The sugarcane bagasse was pre-treated by washing and vacuum drying, crushed by a multifunctional crusher, sieved by a standard test sieve, and then weighed into a 250 mL conical flask containing a 2.5 mol / L citric acid solution, wherein the mass fraction of the sugarcane bagasse was 0.4%. The conical flask was placed in a magnetic stirrer and immersed in a constant temperature 80° C. water bath for 3 h to obtain a citric acid-sugarcane bagasse extract.

[0142] (2) The lithium cobalt oxide positive electrode material is placed in a citric acid-bagasse leachate, wherein the solid-liquid ratio is 15 g / L, and the valuable metals are leached out by ultrasonic treatment at a constant temperature of 80° C. to obtain a leachate containing the valuable metals.

[0143] (3) Precipitating the valuable metals in the leaching solution containing the valuable metals by chemical precipitation method, and testing the recovery rate of the valuable metals.

[0144] Comparative Example 9

[0145] A method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials comprises the following steps:

[0146] (1) The sugarcane bagasse was pre-treated by washing and vacuum drying, crushed by a multifunctional crusher, sieved by a standard test sieve, and then weighed into a 250 mL conical flask containing a 2.5 mol / L citric acid solution, wherein the mass fraction of the sugarcane bagasse was 0.4%. The conical flask was placed in a magnetic stirrer and immersed in a constant temperature 80° C. water bath for 3 h to obtain a citric acid-sugarcane bagasse extract.

[0147] (2) The lithium cobalt oxide positive electrode material is placed in a citric acid-bagasse leachate, wherein the solid-liquid ratio is 35 g / L, and the valuable metals are leached out by ultrasonic treatment at a constant temperature of 80° C. to obtain a leachate containing the valuable metals.

[0148] (3) Precipitating the valuable metals in the leaching solution containing the valuable metals by chemical precipitation method, and testing the recovery rate of the valuable metals.

[0149] Comparative Example 10

[0150] A method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials comprises the following steps:

[0151] (1) The sugarcane bagasse was pre-treated by washing and vacuum drying, crushed by a multifunctional crusher, sieved by a standard test sieve, and then weighed into a 250 mL conical flask containing a 2.5 mol / L citric acid solution, wherein the mass fraction of the sugarcane bagasse was 0.4%. The conical flask was placed in a magnetic stirrer and immersed in a constant temperature 80° C. water bath for 3 h to obtain a citric acid-sugarcane bagasse extract.

[0152] (2) The lithium cobalt oxide positive electrode material is placed in a citric acid-bagasse leaching solution, wherein the solid-liquid ratio is 25 g / L, and constant temperature ultrasound is applied for 1 hour to leach out the valuable metals to obtain a leaching solution containing the valuable metals.

[0153] (3) The valuable metals in the leaching solution containing the valuable metals are precipitated by chemical precipitation method, and the recovery rate of the valuable metals is tested.

[0154] Comparative Example 11

[0155] A method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials comprises the following steps:

[0156] (1) The sugarcane bagasse was pre-treated by washing and vacuum drying, crushed by a multifunctional crusher, sieved by a standard test sieve, and then weighed into a 250 mL conical flask containing a 2.5 mol / L citric acid solution, wherein the mass fraction of the sugarcane bagasse was 0.4%. The conical flask was placed in a magnetic stirrer and immersed in a constant temperature 80° C. water bath for 3 h to obtain a citric acid-sugarcane bagasse extract.

[0157] (2) The lithium cobalt oxide positive electrode material is placed in a citric acid-bagasse leaching solution, wherein the solid-liquid ratio is 25 g / L, and constant temperature ultrasound is applied for 2 hours to leach the valuable metals to obtain a leaching solution containing the valuable metals.

[0158] (3) The valuable metals in the leaching solution containing the valuable metals are precipitated by chemical precipitation method, and the recovery rate of the valuable metals is tested.

[0159] Comparative Example 12

[0160] A method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials comprises the following steps:

[0161] (1) The sugarcane bagasse was pre-treated by washing and vacuum drying, crushed by a multifunctional crusher, sieved by a standard test sieve, and then weighed into a 250 mL conical flask containing a 2.5 mol / L citric acid solution, wherein the mass fraction of the sugarcane bagasse was 0.4%. The conical flask was placed in a magnetic stirrer and immersed in a constant temperature 80° C. water bath for 3 h to obtain a citric acid-sugarcane bagasse extract.

[0162] (2) The lithium cobalt oxide positive electrode material is placed in a citric acid-bagasse leaching solution, wherein the solid-liquid ratio is 25 g / L, and constant temperature ultrasound is applied for 3 hours to leach the valuable metals to obtain a leaching solution containing the valuable metals.

[0163] (3) The valuable metals in the leaching solution containing the valuable metals are precipitated by chemical precipitation method, and the recovery rate of the valuable metals is tested.

[0164] Comparative Example 13

[0165] A method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials comprises the following steps:

[0166] (1) The sugarcane bagasse was pre-treated by washing and vacuum drying, crushed by a multifunctional crusher, sieved by a standard test sieve, and then weighed into a 250 mL conical flask containing a 2.5 mol / L citric acid solution, wherein the mass fraction of the sugarcane bagasse was 0.4%. The conical flask was placed in a magnetic stirrer and immersed in a constant temperature 80° C. water bath for 3 h to obtain a citric acid-sugarcane bagasse extract.

[0167] (2) The lithium cobalt oxide positive electrode material is placed in a citric acid-bagasse leaching solution, wherein the solid-liquid ratio is 25 g / L, and constant temperature ultrasound is applied for 4 hours to leach the valuable metals to obtain a leaching solution containing the valuable metals.

[0168] (3) The valuable metals in the leaching solution containing the valuable metals are precipitated by chemical precipitation method, and the recovery rate of the valuable metals is tested.

[0169] Results Analysis

[0170] The invention determines the optimal leaching conditions of valuable metals in the positive electrode materials of waste lithium cobalt oxide batteries through single factor experiments.

[0171] Inductively coupled plasma (ICP) spectrometry was used to measure the concentration of valuable metals in the leachate and calculate the leaching efficiency of the valuable metals. Set different citric acid concentrations (1.0mol / L, 1.5mol / L, 2.0mol / L, 2.5mol / L, 3.0mol / L), reducing agent mass fraction (0, 0.2%, 0.4%, 0.6%, 0.8%, 1.0%), solid-liquid ratio (10g / L, 15g / L, 20g / L, 25g / L, 30g / L, 35g / L), reaction temperature (50℃, 60℃, 70℃, 80℃, 90℃) and reaction time (1h, 2h, 3h, 4h, 5h, 6h, 6.5h) to explore the effects of different citric acid concentrations, reducing agent (bagasse) mass fraction, solid-liquid ratio, reaction temperature and reaction time on the leaching rate of valuable metals, and find out the optimal conditions for leaching valuable metals. The technical roadmap is as follows: Figure 2 shown.

[0172] Figure 3 The figure shows the effect of different citric acid concentrations on the metal leaching rate in cobalt-cobalt lithium batteries. It can be seen from the figure that with the increase of citric acid concentration, the leaching rates of cobalt and lithium continue to increase. When the citric acid concentration increases from 2.5 mol / L to 3.0 mol / L, the cobalt leaching rate decreases. The reason may be that cobalt and excess citric acid undergo coordination reaction, which reduces the concentration of cobalt ions in the solution. The results show that when the citric acid concentration is 2.5 mol / L, the cobalt leaching rate can reach up to 99%, and the lithium leaching rate can reach 94.64%.

[0173] Figure 4 This figure shows the effect of different reaction temperatures on the metal leaching rate in cobalt-acid lithium batteries. It can be seen from the figure that with the increase of reaction temperature, the leaching rates of cobalt and lithium increase significantly, the leaching rate of cobalt increases from 67.25% to 99.2%, and the leaching rate of lithium increases from 62.66% to 96.52%. When the reaction temperature increases from 80°C to 90°C, the leaching rate of cobalt is 99.2%, and the leaching rate of lithium is 96.52%. Compared with 80°C, the leaching rate of cobalt is almost unchanged, and the leaching rate of lithium increases slightly. This optimal condition should comprehensively consider the recovery value of a small amount of lithium and the energy consumption cost.

[0174] Figure 5 This figure shows the effect of different reaction times on the leaching of metals in lithium cobalt oxide batteries. It can be seen from the figure that with the increase of reaction time, the leaching rate of cobalt increases from 70.25% to 99.15%, and the leaching rate of lithium increases from 82.19% to 94.89%. In comparison, the reaction time has a greater impact on the leaching rate of cobalt. When the reaction time increases from 6h to 6.5h, the leaching rates of cobalt and lithium do not change significantly. The results show that the leaching effect of cobalt and lithium is best when the reaction time is 6h.

[0175] Figure 6 Figure 2 shows the effect of different bagasse mass fractions on the metal leaching rate in cobalt-ion batteries. It can be seen from the figure that with the addition of bagasse, the leaching effect on cobalt is very obvious. Compared with cobalt, the addition of bagasse has less effect on lithium. This may be due to the hydrolysis of cellulose in bagasse into reducing sugars, which converts Co 3+ Become Co 2+， It is more conducive to the leaching of cobalt ions, but when the mass fraction of bagasse exceeds 0.4%, the leaching rates of cobalt and lithium show a downward trend. It may be that too much bagasse absorbs a small amount of leached metal ions, resulting in a decrease in their leaching concentration. The results show that when the mass fraction of bagasse is 0.4%, the leaching rate of cobalt is 99% and the leaching rate of lithium is 94.64%, which is the optimal bagasse mass fraction ratio.

[0176] Figure 7 This figure shows the effect of different solid-liquid ratios on the metal leaching rate in lithium cobalt oxide batteries. It can be seen from the figure that with the increase of the solid-liquid ratio, the leaching rate of cobalt increases, and the leaching rate of lithium increases slightly. The leaching rate of cobalt is the highest when the solid-liquid ratio is 25g / L. When the solid-liquid ratio exceeds 25g / L, the metal leaching rate decreases. At this time, part of the lithium cobalt oxide may not be fully reacted. The results show that the metal leaching rate is best when the solid-liquid ratio is 25g / L.

[0177] Under the optimal experimental conditions, the optimal leaching rate of cobalt is 99.0%, and the optimal leaching rate of lithium is 94.64%. The prior art uses corn platycodon as a reducing agent, and the optimal leaching rate of cobalt is 84%, and the optimal leaching rate of lithium is 98%. However, the price of cobalt is much more expensive than that of lithium, and cobalt is more toxic, and the recycling significance and recycling value are greater. Therefore, the present invention mainly focuses on the leaching of cobalt, and the leaching rate of cobalt is 15% higher than that of the prior art.

[0178] In summary, the present invention uses bagasse to recycle waste lithium-ion batteries. Bagasse contains more carbohydrates, such as cellulose and hemicellulose. Under acidic conditions, cellulose and hemicellulose will be hydrolyzed to produce reducing sugars, which enhances the reducing property of the leaching system and is beneficial to improving the leaching rate of valuable metals.

[0179] It should be noted that when the present invention involves a numerical range, it should be understood that the two endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as those in the embodiments, in order to avoid redundancy, the present invention describes a preferred embodiment. Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the attached claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0180] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials, characterized in that: The following steps are involved: Pre-treating the waste lithium-ion batteries to separate the positive electrode materials, and post-treating the positive electrode materials to obtain the post-treated positive electrode materials; Pre-treating bagasse, adding citric acid solution to the pre-treated bagasse, soaking at a constant temperature, and obtaining bagasse-citric acid leaching solution; The post-treated positive electrode material is placed in the bagasse-citric acid leaching solution, and subjected to ultrasonic heating reaction, so that the cellulose and hemicellulose in the bagasse are hydrolyzed in an acidic environment to generate reducing sugars, thereby enhancing the reducing property of the leaching system, leaching the valuable metals, and obtaining a leaching solution containing the valuable metals; The valuable metals in the leaching solution containing the valuable metals are precipitated by chemical precipitation to achieve the recovery of the valuable metals.

2. The method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials according to claim 1, characterized in that: The concentration of the citric acid solution is 2.0 mol / L to 3.0 mol / L.

3. The method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials according to claim 1, characterized in that: In the bagasse-citric acid leaching solution, the mass fraction of bagasse is 0.2% to 1.0%.

4. The method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials according to claim 1, characterized in that: The volume ratio of the post-processed positive electrode material to the citric acid solution is 25g-30g:1L.

5. The method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials according to claim 1, characterized in that: The heating reaction temperature is 80°C to 90°C.

6. The method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials according to claim 1, characterized in that: The heating reaction time is 5h to 6.5h.

7. The method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials according to claim 1, characterized in that: The valuable metal is cobalt, lithium, nickel, manganese or copper.

8. The method for separating and recovering valuable metals from waste lithium-ion battery positive electrode materials according to claim 1, characterized in that: The pretreatment method of waste lithium-ion batteries is: use sodium hydroxide solution to discharge the waste lithium-ion batteries and perform voltage testing. When the voltage is lower than 1.5V, disassemble them and separate the positive electrode materials.

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