Gluconobacter oxydans for leaching waste lithium iron phosphate battery and leaching method thereof

Abstract

The invention discloses application of gluconobacter oxydans to leaching of waste lithium iron phosphate batteries and a leaching method of the gluconobacter oxydans, and belongs to the technical field of waste battery metal recovery treatment, and lixivium for leaching extraction comprises the gluconobacter oxydans, metabolites of the gluconobacter oxydans and ascorbic acid. Ascorbic acid is added to cooperate with gluconobacter oxydans to enhance the leaching effect. Compared with other non-strongly acidophilic bacteria, the ascorbic acid synergistic gluconobacter oxydans has the advantages of short time, selectivity and high efficiency on the leaching effect of valuable metals in the waste lithium iron phosphate batteries. The method is carried out at a relatively mild pH value, and a new way for applying the gluconobacter oxydans is opened up.

Description

Technical Field

[0001] The invention belongs to the field of metal recovery and treatment of waste batteries, and particularly relates to a Gluconobacter oxidans used for leaching waste lithium iron phosphate batteries and a leaching method thereof. Background Art

[0002] Lithium iron phosphate batteries are a type of lithium-ion battery. They are widely used in energy storage, automobiles, and electronics due to their high safety, long cycle life, low cost, and good stability. With technological advances, their energy density and structure have been optimized, and market demand has grown rapidly. According to TrendForce's 2022 lithium battery market analysis report, the market share of lithium iron phosphate batteries will increase from 27% in 2019 to 46% in 2022, and is expected to reach 64% in 2025. The life of lithium iron phosphate batteries is about 5-8 years, which indicates that there will be more waste lithium iron phosphate batteries to be processed in the future.

[0003] Waste lithium iron phosphate batteries are composed of shells, positive and negative electrode materials, separators and electrolytes, etc. They contain metal resources such as lithium, copper, aluminum and iron oxides, as well as harmful substances such as polymers, organic electrolytes, and fluorine. Therefore, the recycling of waste lithium iron phosphate batteries can effectively reduce the waste of metal resources and avoid environmental pollution.

[0004] There are currently three main methods for recycling waste lithium-ion batteries: direct regeneration, pyrometallurgy, and hydrometallurgy. Direct regeneration mainly restores the electrochemical properties of waste lithium-ion batteries by replenishing lithium through calcination, soaking, and electrochemical lithiation. Pyrometallurgy is the recovery of metals from waste lithium-ion batteries through a high-temperature smelting reduction process, in which the valuable metals are reduced and recovered as alloys. Hydrometallurgical leaching involves the use of inorganic acids, organic acids, etc. to dissolve valuable metals from waste lithium-ion batteries, and then recovering the metals. Bioleaching is a type of hydrometallurgy that uses microbial metabolites to convert insoluble cathode materials into soluble metal ions, and then recovers the metals through extraction or chemical precipitation.

[0005] The direct regeneration method has high requirements on the quality of the cathode materials of waste batteries and strict requirements on battery pretreatment. It has not yet achieved large-scale commercialization in the recovery of valuable metals from waste lithium iron phosphate batteries; pyrometallurgy has the disadvantages of easily producing toxic gases, polluting the environment and consuming high energy; chemical hydrometallurgy uses a large amount of chemicals, produces strong acid and alkali waste liquid, which is easy to pollute the environment, and requires subsequent treatment of a large amount of waste liquid, and the economic benefits are average. Compared with the above-mentioned recycling processes, the key advantages of bioleaching of waste lithium iron phosphate batteries are: compared with the direct regeneration method, it has a simple operation process; compared with pyrometallurgy, it does not require high temperature and high pressure conditions, thereby reducing energy consumption and having economic benefits; compared with chemical hydrometallurgy, it produces biogenic acids through microbial metabolism, avoiding the use of a large amount of chemicals and reducing the impact on environmental pollution.

[0006] In the field of bioleaching of waste lithium iron phosphate batteries, current research mainly focuses on the use of strong acidophilic bacteria, such as Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and Leptospirillum ferrooxidans. Recently, there have also been reports of non-strong acidophilic bacteria. The Chinese patent application number 202410910825.0 discloses Lactobacillus acidophilus, and Harshit M, Guillermo H, Fariborz F, et al. A novel neutrophilic bacteria based process for selectiveLiFePO4 cathode recycling [J]. Resources, Conservation&Recycling, 2023, 195 discloses Thiobacillus thiooxidans. Gluconobacter oxidans is currently mainly used in the food industry such as fermentation to make vinegar, medical and pharmaceutical industries, etc., and has not been reported in the bioleaching of waste lithium iron phosphate batteries.

[0007] The optimal culture pH value of strong acidophilic bacteria currently used in bioleaching is about 1.0-2.5, so inorganic acids are needed to adjust the pH value of bacterial culture medium, which not only increases the amount of chemicals used, but also increases the cost of equipment maintenance; in addition, the kinetics of bioleaching are slow, and waste lithium iron phosphate batteries will also inhibit the growth of microorganisms. Therefore, it is crucial to develop a relatively mild and efficient bioleaching method to recover valuable metals in waste lithium iron phosphate batteries. Summary of the invention

[0008] In view of the problems in the prior art, the purpose of the present invention is to provide a microorganism for biological leaching of waste lithium iron phosphate batteries, wherein the microorganism is Gluconobacter oxidans, and a method for efficiently leaching waste lithium iron phosphate batteries with the Gluconobacter oxidans is provided.

[0009] The negative electrode material of waste lithium iron phosphate batteries is graphite, and the recovery value of the negative electrode material is lower than that of the positive electrode material. Therefore, this method only performs bioleaching on the valuable metals in the positive electrode material.

[0010] The present invention provides Gluconobacter oxidans for leaching waste lithium iron phosphate batteries. The Gluconobacter oxidans is used for leaching and extracting lithium and iron in waste lithium iron phosphate batteries. Gluconobacter oxidans is an aerobic Gram-negative bacterium with a biosafety level of one, and mainly metabolizes to produce organic acids such as gluconic acid.

[0011] The Gluconobacter oxidans is used to leach waste lithium iron phosphate batteries. The leaching solution used for leaching and extraction includes Gluconobacter oxidans and its metabolites and ascorbic acid. The leaching effect is enhanced by the ascorbic acid cooperating with Gluconobacter oxidans. Ascorbic acid is widely present in fresh vegetables and fruits and has high biodegradability. Ascorbic acid can remove active oxygen in bacteria and is beneficial to the growth of microorganisms. Ascorbic acid is used as an acid agent to dissociate and produce hydrogen ions, thereby promoting the leaching of waste lithium iron phosphate metal.

[0012] Compared with other non-strong acidophilic bacteria, the ascorbic acid cooperates with Gluconobacter oxidans to have a short-term, selective and efficient leaching effect on valuable metals in waste lithium iron phosphate batteries.

[0013] The present invention provides a leaching method for leaching waste lithium iron phosphate batteries using Gluconobacter oxidans, comprising the following steps: Step 1: Obtaining leached powder of spent phosphoric acid batteries for bioleaching; Step 2: domesticating Gluconobacter oxidans; Step 3: Add the oxidizing Gluconobacter oxydans domesticated in step 2 and the leached powder in step 1 into the culture medium to leach lithium and iron.

[0014] In the step 1, the waste lithium iron phosphate battery is disassembled, the positive electrode binder is dissolved, the positive electrode material is removed from the aluminum foil, crushed and ground to pass through a 100-mesh sieve, and the battery powder for bioleaching is obtained; In step 3, the leaching temperature is 30°C, the time is 7 days, the shaking speed is 150 rpm, the solid-liquid ratio is 10.0 g / L, and the initial bacterial concentration is 10 7 cells / mL, the pH value of the leaching system is 3.0-5.1; The culture medium components include: 5.0 g / L yeast extract, 3.0 g / L peptone, 25.0 g / L mannitol, and 10.0 g / L glucose. The initial pH value of the culture medium is about 6.1.

[0015] Bioleaching includes the following three methods: The one-step method is to directly add the microorganisms domesticated and adapted to waste lithium iron phosphate batteries into the culture medium system together with the powder, and bacterial growth and metal leaching are carried out simultaneously; the two-step method is to first culture the microorganisms domesticated and adapted to waste lithium iron phosphate batteries to the logarithmic growth phase, and then add the battery powder for leaching; the spent culture medium method is to culture the microorganisms domesticated and adapted to waste lithium iron phosphate batteries to the logarithmic growth stable phase, and then obtain the culture solution containing bacterial metabolites by centrifugation and filtration of the bacterial culture, which is used for the leaching of waste lithium iron phosphate batteries.

[0016] The leaching method for leaching waste lithium iron phosphate batteries using Gluconobacter oxidans, in the step 2, firstly culture the domesticated Gluconobacter oxidans in a culture medium until it is in a logarithmic growth phase, and then add the battery powder into the culture medium to leach lithium and iron.

[0017] The leaching method of using Gluconobacter oxidans to leach waste lithium iron phosphate batteries has a leaching system in which, after 7 days of leaching, the percentage of lithium ions in the leaching solution can reach 59.2%, while the percentage of iron ions is only 0.6%.

[0018] The leaching method for leaching waste lithium iron phosphate batteries using the Gluconobacter oxidans, when the domesticated Gluconobacter oxidans is cultured in a culture medium until it is in a logarithmic growth phase, battery powder and ascorbic acid are simultaneously added to the culture medium to leach lithium and iron.

[0019] The above-mentioned leaching method of using Gluconobacter oxidans to leach waste lithium iron phosphate batteries, adding 0.075 M ascorbic acid can significantly improve the leaching effect. After 4 days of leaching, the percentage of lithium ions in the leachate can reach 97.2%, while the percentage of iron ions is only 17.1%, which indicates that the leaching effect of ascorbic acid and Gluconobacter oxidans on lithium and iron in waste lithium iron phosphate batteries is short-term, selective and efficient.

[0020] The leaching method of using Gluconobacter oxidans to leach waste lithium iron phosphate batteries, wherein the domestication of Gluconobacter oxidans in step 2 comprises the following specific steps: Inoculate Gluconobacter oxidans in the culture medium and add the leaching powder described in step 1 to control the solid-liquid ratio to 0.5 g / L and the initial bacterial concentration to 10 7 cells / mL, cultured at 30°C until the bacterial concentration reached 10 8 At this time, take out part of the bacterial solution and transfer it to new culture medium, keep the solid-liquid ratio unchanged, and subculture at a ratio of 1 mL of bacterial solution to 20 mL of new culture medium until the bacterial concentration is 10 8cells / mL, and repeat the above steps with the subcultured bacterial solution. The difference is that the solid-liquid ratio is changed to 1.0 g / L, that is, the solid-liquid ratio is increased by 0.5 g / L every two cultures, and so on, until the solid-liquid ratio is 10.0 g / L and the bacterial concentration reaches and stabilizes at 10 8 cells / mL, the domestication process is completed and the domesticated Gluconobacter oxydans is obtained.

[0021] Compared with the existing method, the present invention has the following beneficial effects: 1) Innovation of bacterial strains: Innovatively apply Gluconobacter oxidans to the bioleaching of positive electrode materials of waste lithium iron phosphate batteries. It does not rely on traditional strong acidophilic bacteria, avoids the generation of strong acidic wastewater, and leaches valuable metals without causing serious acid damage to the environment and equipment.

[0022] 2) Short-term, high-efficiency and selective leaching: In the process of biological leaching of Gluconobacter oxidans, different leaching methods were used. When the solid-liquid ratio was 10.0 g / L, the two-step leaching method had the best leaching effect. After 7 days of leaching, the percentage of lithium ions in the leaching solution could reach 59.2%, while the percentage of iron ions was only 0.6%; after the bacteria in the two-step experiment entered the logarithmic growth phase, 0.075 M ascorbic acid was added. After 4 days of leaching, the percentage of lithium ions in the leaching solution could reach 97.2%, while the percentage of iron ions was only 17.1%. The results show that compared with other non-strong acidophilic bacteria, this bacterium has a short-term, high-efficiency and selective leaching effect on lithium and iron in waste lithium iron phosphate batteries.

[0023] 3) This method uses biological organic acid in the leaching process, and the pH value fluctuates in the range of 3.0-5.1. Compared with strong acidophilic bacteria leaching, it is milder and more economical than traditional chemical leaching and can reduce pollution to the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention is a flow chart of a method for leaching waste lithium iron phosphate batteries using Gluconobacter oxidans. DETAILED DESCRIPTION

[0025] The present invention selects Gluconobacter oxidans and domesticates it with waste lithium iron phosphate batteries, with a solid-liquid ratio of 10.0 g / L, adopts different leaching methods and determines the best leaching method, and adds ascorbic acid on the basis of the best leaching method to enhance the leaching effect. The specific process is shown in the attached Figure 1The culture medium used in each example includes: 5.0 g / L yeast extract, 3.0 g / L peptone, 25.0 g / L mannitol, 10.0 g / L glucose, and the initial pH value of the culture medium is about 6.1. The experimental results of the following examples are obtained by averaging the results of three repeated experiments.

[0026] Example 1

[0027] A method for leaching waste lithium iron phosphate batteries by using Gluconobacter oxidans, which adopts a one-step leaching method and specifically comprises the following steps: Step 1: Obtaining Spent Battery Phosphoric Acid Leaching Powder for Bioleaching Waste lithium iron phosphate batteries were purchased from a scrap recycling station. They were completely discharged by soaking them in 1.0 mol / L sodium chloride solution. The metal shell was cut with a cutting machine and disassembled into individual batteries, and then dried at 60 °C for further disassembly of the battery. During the disassembly process, the shell and the plastic separator inside were first peeled off, the negative electrode material was removed, and the positive electrode material was left. The positive electrode material was then cut into square blocks of about 5 cm and soaked in N-methylpyrrolidone (NMP) solution to dissolve the binder (polyvinylidene fluoride, PVDF). After dissolving at 60 °C for 3 hours, the dissolved positive electrode material was washed three times with distilled water. After drying at 60 °C, it was placed in a 1.5 % (w / v) sodium hydroxide solution for 0.5 hours under a 10 % (w / v) solid-liquid ratio. The positive electrode material was separated from the aluminum foil and dried at 60 °C. Subsequently, it was crushed in a powder grinder and ground in a mortar, and passed through a 100-mesh sieve to obtain waste lithium iron phosphate battery powder for leaching experiments. The obtained cathode material powder was digested using a chemical digestion method (HNO3:HC1O4:HF = 2:1:2) (v / v), and the contents of lithium ions and iron ions in the digestion solution were determined by inductively coupled plasma optical emission spectrometry (ICP–OES), which were 35.2 mg / g and 283.1 mg / g, respectively.

[0028] Step 2: Acclimate Gluconobacter oxydans The medium components include: yeast extract 5.0 g / L, peptone 3.0 g / L, mannitol 25.0 g / L, glucose 10.0 g / L. The initial pH value of the medium is about 6.1; Inoculate Gluconobacter oxidans in the culture medium and add the leaching powder described in step 1, control the solid-liquid ratio to 0.5 g / L, and the initial bacterial concentration to 10 7 cells / mL, cultured at 30°C until the bacterial concentration reached 10 8At this time, take out part of the bacterial solution and transfer it to new culture medium, keep the solid-liquid ratio unchanged, and subculture at a ratio of 1 mL of bacterial solution to 20 mL of new culture medium until the bacterial concentration is 10 8 cells / mL, and repeat the above steps with the subcultured bacterial solution. The difference is that the solid-liquid ratio is changed to 1.0 g / L, that is, the solid-liquid ratio is increased by 0.5 g / L every two cultures, and so on, until the solid-liquid ratio is 10.0 g / L and the bacterial concentration reaches and stabilizes at 10 8 cells / mL, the domestication process is completed and the domesticated Gluconobacter oxydans is obtained.

[0029] Step 3: Leaching One-step method: Add 200 mL of culture medium into a 250 mL conical flask and inoculate the domesticated Gluconobacter oxydans into the culture medium, controlling the initial bacterial concentration to 1×10 7 cells / mL, added leaching powder for microbial leaching, and controlled the solid-liquid ratio to 10.0 g / L; the start of the leaching experiment was recorded as 0 hours, and placed on a shaking table at 30 °C and 150 rpm. The leaching experiment lasted for 7 days, and samples were taken every 0.5 days in the first 3 days of leaching, and every other day thereafter; during the sampling process, the pH value and bacterial concentration changes were detected simultaneously. The former value fluctuated in the range of 4.0-5.1, and the latter value fluctuated in the range of 1×10 7 -2.05×10 8 cells / mL, it showed a trend of first increasing and then decreasing; the maximum gluconic acid content in the leaching process was measured by high performance liquid chromatography (HPLC) to be 583 mg / L; the concentrations of lithium ions and iron ions in the leachate were measured by ICP-OES, and then the leaching percentage was calculated. After 7 days, the percentage of lithium ions in the leachate could reach 42.5%, while the percentage of iron ions was only 0.8%; the results showed that this bacteria had a selective leaching effect on lithium and iron in waste lithium iron phosphate batteries.

[0030] Example 2

[0031] A method for leaching waste lithium iron phosphate batteries by using Gluconobacter oxidans, which adopts a two-step leaching method and specifically comprises the following steps: Step 1: Same as Example 1.

[0032] Step 2: Acclimate Gluconobacter oxydans Same as Example 1.

[0033] Step 3: Leaching Two-step method: Add 200 mL of culture medium into a 250 mL conical flask, inoculate the domesticated Gluconobacter oxydans into the culture medium, and control the initial bacterial concentration to 1×10 7 cells / mL, and after culturing in a shaker at 30 °C and 150 rpm for 20 hours, the bacterial concentration reached 2.25×10 8 cells / mL, and its growth entered the logarithmic growth phase. The leaching powder used for biological leaching was added to control the solid-liquid ratio to 10.0 g / L. The start of the leaching experiment was recorded as 0 hours, and it was placed on a shaking table at 30 ℃ and 150 rpm. The leaching experiment lasted for 7 days. Samples were taken every 0.5 days in the first 3 days of leaching, and every other day thereafter. During the sampling process, the pH value and bacterial concentration changes were detected simultaneously. The former value fluctuated in the range of 3.4-4.5, and the latter value fluctuated in the range of 1.25×10 8 -2.25×10 8 cells / mL, it showed a trend of first decreasing, then increasing, and then decreasing again; the maximum gluconic acid content in the leaching process was measured by HPLC to be 835 mg / L; the concentrations of lithium ions and iron ions in the leachate were measured by ICP-OES, and then the leaching percentage was calculated. After 7 days, the percentage of lithium ions in the leachate could reach 59.2%, while the percentage of iron ions was only 0.6%; the results showed that this bacteria had a selective leaching effect on lithium and iron in waste lithium iron phosphate batteries.

[0034] Example 3

[0035] A method for leaching waste lithium iron phosphate batteries by using Gluconobacter oxidans, which adopts a waste culture medium method, specifically comprises the following steps: Step 1: Same as Example 1.

[0036] Step 2: Acclimate Gluconobacter oxydans Same as Example 1.

[0037] Step 3: Leaching Spent culture medium method: To prevent the filtrate of Gluconobacter oxidans metabolites from being less than 200 mL, add 220 mL of culture medium into a 250 mL conical flask and inoculate the domesticated Gluconobacter oxidans into the culture medium. The initial bacterial concentration is controlled to be 1×10 7 cells / mL; after culturing in a shaker at 30 °C and 150 rpm for 72 hours, the bacterial concentration reached 2.4×10 8cells / mL, with a pH value of 3.1, which is in the logarithmic growth stable stage; centrifuge at 10000 rpm, 10 min, take the supernatant after centrifugation and filter it in a vacuum filter, then filter the filtered liquid with a water filter head (0.22 μm) to obtain the filtrate of Gluconobacter oxidans metabolites; take 200 mL of the filtrate and add it to a 250 mL conical flask, add the leaching powder used for biological leaching, and control the solid-liquid ratio to 10.0 g / L; when the leaching experiment starts, it is recorded as 0 hours, and it is placed on a shaking table at 30 ℃ and 150 rpm. The leaching experiment lasts for 7 days, and samples are taken every 0.5 days for the first 3 days of leaching, and every other day thereafter; because the system uses bacterial metabolites for leaching and does not contain bacteria, it is only necessary to detect the pH value change during the leaching process, and its value fluctuates within the range of 3.1-4.3; the maximum gluconic acid content during the leaching process measured by HPLC is 995 mg / L; the concentrations of lithium ions and iron ions in the leachate were measured by ICP-OES, and then the leaching percentage was calculated. After 7 days, the percentage of lithium ions in the leachate could reach 58.2%, while the percentage of iron ions was only 1.3%; the results showed that this type of bacteria has a selective leaching effect on lithium and iron in waste lithium iron phosphate batteries.

[0038] Example 4

[0039] A method for leaching waste lithium iron phosphate batteries by leaching Gluconobacter oxidans, using a two-step leaching method and adding ascorbic acid, the specific operating steps are as follows: Step 1: Same as Example 1.

[0040] Step 2: Acclimate Gluconobacter oxydans Same as Example 1.

[0041] Step 3: Leaching Two-step method: Add 200 mL of culture medium into a 250 mL conical flask, inoculate the domesticated Gluconobacter oxydans into the culture medium, and control the initial bacterial concentration to 1×10 7 cells / mL, and after culturing in a shaker at 30 °C and 150 rpm for 20 hours, the bacterial concentration reached 2.25×10 8cells / mL. After the bacteria entered the logarithmic growth phase, 2.7 g ascorbic acid and 2.0 g of used lithium iron phosphate batteries were added to control the solid-liquid ratio to 10.0 g / L. The start of the leaching experiment was recorded as 0 hours. The cells were placed in a shaking table at 30 °C and 150 rpm. The leaching experiment lasted for 7 days. Samples were taken every 0.5 days in the first 3 days of leaching, and every other day thereafter. During the sampling process, the pH value and bacterial concentration changes were detected simultaneously. The former fluctuated in the range of 3.0-3.7, which was caused by the addition of ascorbic acid, and the latter fluctuated in the range of 9.5×10 7 -2.25×10 8 cells / mL, it showed a trend of first decreasing, then increasing and then decreasing again; the maximum gluconic acid content in the leaching process was measured by HPLC to be 570 mg / L; the concentrations of lithium ions and iron ions in the leachate were measured by ICP-OES, and then the leaching percentage was calculated. After 4 days, the percentage of lithium ions in the leachate could reach 97.2%, while the percentage of iron ions was only 17.1%; the results showed that compared with other non-strong acidophilic bacteria, this bacteria has a short-term, high-efficiency and selective leaching effect on lithium and iron in waste lithium iron phosphate batteries.

[0042] The leaching experiment actually lasted for 7 days. After 4 days, the percentage of lithium ions in the leachate could reach 97.2%. In the following days, the percentage of lithium ions in the leachate was almost stable, so the results after 4 days of the leaching experiment were selected.

[0043] Comparative Example 1 The blank culture medium control experiment of leaching waste lithium iron phosphate batteries with Gluconobacter oxidans was carried out. The specific steps are as follows: Step 1: Same as Example 1.

[0044] Step 2: Leaching 200 mL of culture medium and 2.0 g of used lithium iron phosphate batteries were added to a 250 mL conical flask with a solid-liquid ratio of 10.0 g / L. No Gluconobacter oxidans was added. The start of the leaching experiment was recorded as 0 hour, and it was placed on a shaker at 30 °C and 150 rpm. The leaching experiment lasted for 7 days. Samples were taken every 0.5 days in the first 3 days of leaching, and every other day thereafter. During the sampling process, the pH value was detected at the same time, and its value fluctuated in the range of 6.3-7.2. 2 mL of the leachate was filtered using a water filter (0.22 μm) and placed in a refrigerator at 4 °C for subsequent content detection. The concentrations of lithium ions and iron ions in the leachate were measured by ICP-OES, and then the leaching percentage was calculated. After the experiment, the percentage of lithium ions in the leachate was 7.1%, and the percentage of iron ions was 0.02%.

Claims

1. Gluconobacter oxidans is used to leaching waste lithium iron phosphate batteries, characterized in that: Gluconobacter oxidans is used for leaching and extracting lithium and iron in waste lithium iron phosphate batteries; the leaching solution used for leaching and extraction includes Gluconobacter oxidans and its metabolites and ascorbic acid, and the leaching effect is enhanced by the synergistic effect of ascorbic acid and Gluconobacter oxidans.

2. The leaching method of waste lithium iron phosphate batteries using Gluconobacter oxidans as claimed in claim 1, characterized in that: The following steps are involved: Step 1: Obtaining waste phosphoric acid battery leaching powder for bioleaching; Step 2: domesticating Gluconobacter oxidans; Step 3: Add the oxidizing Gluconobacter oxydans domesticated in step 2 and the leached powder in step 1 into the culture medium to leach lithium and iron.

3. The leaching method of using Gluconobacter oxidans to leach waste lithium iron phosphate batteries as claimed in claim 2, characterized in that: In the step 3, the domesticated Gluconobacter oxidans is first cultured in a culture medium until it is in a logarithmic growth phase, and then the battery powder is added to the culture medium to leach lithium and iron.

4. The leaching method of waste lithium iron phosphate batteries using Gluconobacter oxidans as claimed in claim 3, characterized in that: When the domesticated Gluconobacter oxidans is cultured in a culture medium until it is in a logarithmic growth phase, ascorbic acid and battery powder are simultaneously added to the culture medium to leach lithium and iron.

5. The leaching method of waste lithium iron phosphate batteries using Gluconobacter oxidans as claimed in claim 3, characterized in that: After 7 days of leaching, the percentage of lithium ions in the leaching solution of the leaching system reached 59.2%, while the percentage of iron ions was only 0.6%.

6. The leaching method of waste lithium iron phosphate batteries using Gluconobacter oxidans as claimed in claim 4, characterized in that: Adding 0.075 M ascorbic acid can significantly improve the leaching effect. After 4 days of leaching, the percentage of lithium ions in the leaching solution reached 97.2%, while the percentage of iron ions was only 17.1%.

7. The leaching method for leaching waste lithium iron phosphate batteries using Gluconobacter oxidans as claimed in any one of claims 2 to 6, characterized in that: In the step 1, the waste LFPs are disassembled, the positive electrode binder is dissolved, the positive electrode material is removed from the aluminum foil, crushed and ground and sieved to obtain the battery powder for bioleaching; In step 3, the leaching temperature is 30°C, the time is 7 days, the shaking speed is 150 rpm, the solid-liquid ratio is 10.0 g / L, and the initial bacterial concentration is 10 7 cells / mL, the pH value of the leaching system is 3.0-5.1; The culture medium components include: 5.0 g / L yeast extract, 3.0 g / L peptone, 25.0 g / L mannitol, and 10.0 g / L glucose. The initial pH value of the culture medium is 6.

1.

8. The leaching method of using Gluconobacter oxidans to leach waste lithium iron phosphate batteries as claimed in claim 2, characterized in that: In the step 2, domesticating Gluconobacter oxidans comprises the following specific steps: Inoculate Gluconobacter oxidans in the culture medium and add the leaching powder described in step 1, control the solid-liquid ratio to 0.5 g / L, and the initial bacterial concentration to 10 7 cells / mL, cultured at 30°C until the bacterial concentration reached 10 8 At this time, take out part of the bacterial solution and transfer it to new culture medium, keep the solid-liquid ratio unchanged, and subculture at a ratio of 1 mL of bacterial solution to 20 mL of new culture medium until the bacterial concentration is 10 8 cells / mL, and the subcultured bacterial solution was taken at this time, and the solid-liquid ratio was adjusted to 1.0 g / L, and the initial bacterial concentration was 10 7 cells / mL, cultured at 30°C until the bacterial concentration reached 10 8 cells / mL, and then take out part of the bacterial solution and transfer it to new culture medium, keeping the solid-liquid ratio unchanged, and subculture with 1 mL of bacterial solution corresponding to 20 mL of new culture medium, that is, every 2 cultures, the solid-liquid ratio increases by 0.5 g / L, and so on, until the solid-liquid ratio is 10.0 g / L and the bacterial concentration reaches and stabilizes at 10 8 cells / mL, the domestication process is completed and the domesticated Gluconobacter oxydans is obtained.

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