Biological leaching method of retired ternary lithium battery positive electrode material under combined catalysis of extracellular polymeric substance and Cu < 2 + >

Abstract

The invention discloses a method for bioleaching a retired ternary lithium battery positive electrode material under combined catalysis of an extracellular polymer and Cu < 2 + >, which comprises the following steps: (1) discharging, roasting, disassembling and grinding a retired ternary lithium battery to obtain ternary lithium battery positive electrode material powder; (2) carrying out mixed culture on the Acidithiobacillus ferrooxidans and the Acidithiobacillus thiooxidans, so as to obtain a mixed bacterial solution; (3) extracting an extracellular polymeric substance from the mixed bacterial liquid obtained in the step (2), and adding the extracellular polymeric substance and Cu < 2 + > into the mixed bacterial liquid obtained in the step (2) to obtain a biological leaching agent; and (4) the waste ternary lithium battery powder obtained in the step (1) is added into the biological leaching agent prepared in the step (3) for a biological leaching reaction for 3-7 days, and a biological leaching solution is obtained. According to the method, the bioleaching rate of metal is increased through the extracellular polymeric substance and Cu < 2 + >, operation is easy and convenient to implement, and the catalyst is simple and easy to obtain.

Description

Technical Field

[0001] The present invention belongs to the field of resource recycling and mainly relates to an extracellular polymer and Cu 2+ A method for bioleaching of cathode materials from decommissioned ternary lithium batteries using combined catalysis. Background Art

[0002] Lithium-ion batteries have advantages such as high energy density and long cycle life, and are widely used in power batteries, energy storage systems, and consumer electronics. In recent years, with the vigorous development of new energy vehicles and energy storage materials, the output of lithium-ion batteries has shown explosive growth. Among them, ternary lithium batteries LiNi x Co y Mn z O2 is currently the mainstream high-endurance power battery. With the rapid growth of new energy vehicle ownership, the number of retired power batteries is also increasing year by year. If these batteries are not properly handled, it will result in the waste of valuable metals and may also cause serious health and environmental problems. Waste ternary lithium battery positive electrode materials contain a large amount of valuable metal compounds such as Li, Ni, Co, and Mn. The average content of some metals is much higher than the average grade of the corresponding primary ores in China (Li: 2-5% > 2.75%, Ni: 5-12% > 0.02%, Co: 5-20% > 1.5%), and have extremely high recycling value. Therefore, accelerating the clean and efficient recycling of waste ternary lithium battery positive electrode materials can not only achieve the recycling of limited resources, but also avoid the potential threats of waste ternary lithium battery positive electrode materials to human health and the ecological environment.

[0003] Currently, the main methods for recovering valuable metals from spent ternary lithium battery cathode materials include pyrolysis, wet processing, or a combination of the two. Compared to pyrolysis, wet processing offers simple raw material turnover, a high overall metal recovery rate, and no harmful gas emissions. However, chemical wet processing requires the addition of a significant amount of acid, reducing agents, and other chemical reagents, generating large amounts of corrosive wastewater and causing secondary pollution. Bioleaching utilizes the metabolic products and redox properties of microorganisms during their life activities to induce oxidation and reduction of valuable metal elements in the raw materials, ultimately separating them from other components as ions in aqueous solution or as precipitates. Compared to chemical leaching under equivalent conditions, bioleaching can reduce acid usage by more than half, offering advantages such as environmental friendliness, low cost, and a simple process. However, long leaching times and low metal leaching rates result in slow metal dissolution kinetics, limiting the large-scale application of traditional bioleaching technology in the recycling of spent ternary lithium battery cathode materials.

[0004] Strategies such as constructing composite bacterial communities and adding metal ion catalysts can effectively improve the metal recovery rate and shorten the reaction cycle. However, the tolerance of microorganisms to metal ions is limited. When Cu is used in the bioleaching process, the metal ion2+ 、Ag + When metal ions such as iodine are used as catalysts, their inhibitory and toxic effects on microorganisms pose new challenges to the use of catalysts.

[0005] Extracellular polymers (ECPs) are natural high-molecular polymers secreted onto the cell surface by microorganisms in response to external stimuli during their growth. They are composed of polysaccharides, proteins, and nucleic acids. In studies on bioleaching of sulfide minerals such as chalcopyrite, it was found that ECPs have three main functions: 1) They can generate hydrophobicity and electrostatic forces through their specific functional groups and unique structure, allowing microorganisms to strongly adhere to minerals; 2) The rich functional groups in ECPs can separate and enrich Fe ions, converting Fe 2+ / Fe 3+ Redox cycling is concentrated at the mineral-bacteria microinterface, accelerating the reduction and dissolution of metals through electron transfer. Extracellular polymers (EPs) can encapsulate bacteria, forming a "protective film" that imparts metal resistance and a Rubisco-free carbon fixation pathway, providing energy for mineral bioleaching. EEPs not only increase contact between minerals and microorganisms, providing a medium for mineral redox, but also effectively enhance microorganisms' environmental adaptability and ability to combat metal biotoxicity, making them an optimal solution to addressing low microbial tolerance to metal ions.

[0006] In summary, the method adopted by the present invention is: extracellular polymers extracted from a mixed bacterial population of Thiobacillus ferrooxidans and Thiobacillus thiooxidans are added to 2+ In the system of bioleaching of spent ternary lithium battery cathode materials by mixed bacterial community catalysis, the Cu 2+ and the biological toxicity of dissolved metals, and efficiently leaching valuable metals from waste ternary lithium battery positive electrode materials in a short time. Summary of the Invention

[0007] The present invention aims at the recycling and treatment of retired ternary lithium battery positive electrode materials, and provides an extracellular polymer and Cu 2+ A method for bioleaching of cathode materials from decommissioned ternary lithium batteries using combined catalysis.

[0008] The extracellular polymers and Cu 2+ The combined catalytic bioleaching method for retired ternary lithium battery cathode materials has the following process steps:

[0009] Step 1: Discharge, calcine and disassemble the waste ternary lithium battery to obtain ternary lithium positive electrode material powder;

[0010] Step 2: Add Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans to the culture medium, and culture in a constant temperature shaking incubator at a temperature of 28-32° C. and a rotation speed of 150-200 rpm. When the pH of the culture system is ≤1.2, a mixed bacterial solution is obtained;

[0011] Step 3: Extract extracellular polymers from the mixed bacterial solution obtained in step 2 and then 2+ At the same time, it is added to the mixed bacterial solution in step 2 to prepare a bioleaching agent;

[0012] Step 4: Add the ternary lithium cathode material powder obtained in step 1 to the bioleaching agent prepared in step 3, react for 3-7 days, and obtain a bioleaching solution.

[0013] Furthermore, the culture medium is a modified 9K culture medium, consisting of 3 g / L (NH4)2SO4, 0.5 g / L KCl, 0.1 g / L K2HPO4, 0.5 g / L MgSO4·7H2O, 0.01 g / L Ca(NO3)2, 22.1 g / L green vitriol and 5 g / L sulfur powder.

[0014] Furthermore, the biomass ratio of Thiobacillus ferrooxidans to Thiobacillus thiooxidans in the mixed bacterial liquid is 1:2 to 2:1.

[0015] Furthermore, the method for extracting extracellular polymers comprises the following specific steps:

[0016] Thiobacillus ferrooxidans and Thiobacillus thiooxidans were mixed and cultured in a constant temperature shaking incubator until the pH was ≤ 1.2, and then centrifuged at 10,000 rpm and 4° C. to obtain an extracellular polymer supernatant; after filtering through a 0.22 μm cellulose acetate membrane, the supernatant was purified using a dialysis membrane (3,500 Da) at 4° C. to remove miscellaneous bacteria and impurities; a methanol solution was then added to the supernatant and allowed to stand at 4° C. for precipitation, and the mixture was centrifuged at 10,000 rpm and room temperature. The collected precipitate was freeze-dried to obtain the extracellular polymer of the mixed bacterial solution.

[0017] Furthermore, the amount of the extracellular polymer added is 100 to 300 mg / L.

[0018] Furthermore, the Cu 2+ The addition amount is 0.8~1.2g / L.

[0019] Furthermore, the addition amount of the ternary lithium battery positive electrode material powder is 2-10% W / V.

[0020] In the present invention, the concentration of metal ions is measured by performing inductively coupled plasma emission spectroscopy on the finally obtained biological leaching solution to obtain the leaching rate of the metal elements.

[0021] The beneficial effect of the present invention is that: the method of the present invention adds extracellular polymers and Cu in the leaching process 2+ As a catalyst, it improves the metal leaching rate in the positive electrode active materials of waste ternary lithium batteries. In the general process of metal ion catalytic bioleaching of waste lithium battery positive electrode active materials, with the addition of metal ion catalysts and the continuous dissolution of valuable metal ions, the microbial cells will be subjected to oxidative stress, inhibiting the redox activity of bacteria, hindering the progress of the bioleaching process, and reducing the metal leaching rate. In the present invention, the addition of extracellular polymers effectively improves the environmental adaptability of microorganisms and copes with the biological toxicity of metals, and can increase the contact between minerals and microorganisms, provide a medium for mineral redox, and thus improve the bioleaching rate. The method of the present invention is simple to operate, and utilizes extracellular polymers and Cu 2+ Combined catalysis improves the metal leaching rate in discarded lithium batteries, and the extracellular polymers are derived from the bacteria themselves, which are green and environmentally friendly materials and do not increase the burden on the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 Extracellular polymers and Cu 2+ Combined catalytic bioleaching process for retired ternary lithium battery cathode materials DETAILED DESCRIPTION

[0024] The present invention is described in detail below with reference to the embodiments, but the protection scope of the present invention is not limited to the following embodiments.

[0025] Example 1

[0026] (1) After discharging, roasting, disassembling and grinding, the positive electrode material powder of the ternary lithium battery can be obtained;

[0027] (2) Add 22.1 g / L green vitriol, 5 g / L sulfur powder and 90 mL of 9K medium to a 250 mL conical flask, add 10 mL of a mixed bacterial solution of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans (the ratio of the added biomass is 1:2), and place in a constant temperature shaking incubator for cultivation at a temperature of 30°C and a rotation speed of 170 rpm. When the pH in the culture system is ≤1.2, the mixed bacterial solution can be obtained;

[0028] (3) The mixed bacterial solution obtained in step 2 was centrifuged at 10,000 rpm at 4°C to obtain an extracellular polymer supernatant; after filtering through a 0.22 μm cellulose acetate membrane, it was purified using a dialysis membrane (3500 Da) at 4°C to remove the bacteria and impurities in the supernatant; methanol solution was then added and allowed to settle at 4°C, and centrifuged at 10,000 rpm at room temperature. The collected precipitate was freeze-dried to obtain the extracellular polymer of the mixed bacterial solution. The extracted extracellular polymer was mixed with Cu 2+ Adding the final concentrations of 100 mg / L and 0.8 g / L to the mixed bacterial solution in step 2 to prepare the bioleaching agent;

[0029] (4) 0.2 g (2% W / V) of spent ternary lithium battery cathode material powder was added to a mixed bacterial solution without any additives and cultured for 3-7 days. Samples were taken daily and filtered through a 0.22 μm water filter. The concentrations of lithium, nickel, cobalt, and manganese in the leachate were measured using inductively coupled plasma optical emission spectroscopy (ICP-OES) and the extraction percentages were calculated.

[0030] The results showed that after 7 days of bioleaching, the leaching rate of lithium reached 99.9%, the leaching rate of nickel reached 91.3%, the leaching rate of cobalt reached 92.7%, and the leaching rate of manganese reached 90.1%.

[0031] Example 2

[0032] (1) After discharging, roasting, disassembling and grinding, the positive electrode material powder of the ternary lithium battery can be obtained;

[0033] (2) Add 22.1 g / L green vitriol, 5 g / L sulfur powder and 90 mL of 9K medium to a 250 mL conical flask, add 10 mL of a mixed bacterial solution of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans (the ratio of the added biomass is 1:1), and place in a constant temperature shaking incubator for cultivation at a temperature of 30°C and a rotation speed of 170 rpm. When the pH in the culture system is ≤1.2, the mixed bacterial solution can be obtained;

[0034] (3) The mixed bacterial solution obtained in step 2 was centrifuged at 10,000 rpm at 4°C to obtain an extracellular polymer supernatant; after filtering through a 0.22 μm cellulose acetate membrane, it was purified using a dialysis membrane (3500 Da) at 4°C to remove the bacteria and impurities in the supernatant; methanol solution was then added and allowed to settle at 4°C, and centrifuged at 10,000 rpm at room temperature. The collected precipitate was freeze-dried to obtain the extracellular polymer of the mixed bacterial solution. The extracted extracellular polymer was mixed with Cu 2+ Adding the final concentrations of 200 mg / L and 1.2 g / L to the mixed bacterial solution in step 2 to prepare the bioleaching agent;

[0035] (4) 0.6 g (6% W / V) of spent ternary lithium battery cathode material powder was added to a bioleaching agent and incubated for 3-7 days to obtain the bioleaching agent. Samples were taken daily and filtered through a 0.22 μm water filter. The concentrations of lithium, nickel, cobalt, and manganese in the leachate were measured using inductively coupled plasma optical emission spectroscopy (ICP-OES), and the extraction percentages were calculated.

[0036] The results showed that after 7 days of bioleaching, the leaching rate of lithium reached 99.9%, the leaching rate of nickel reached 91.1%, the leaching rate of cobalt reached 91.4%, and the leaching rate of manganese reached 91.3%.

[0037] Example 3

[0038] (1) After discharging, roasting, disassembling and grinding, the positive electrode material powder of the ternary lithium battery can be obtained;

[0039] (2) Add 22.1 g / L green vitriol, 5 g / L sulfur powder and 90 mL of 9K medium to a 250 mL conical flask, add 10 mL of a mixed bacterial solution of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans (the ratio of the added biomass is 2:1), and place in a constant temperature shaking incubator for cultivation at a temperature of 30°C and a rotation speed of 170 rpm. When the pH in the culture system is ≤1.2, the mixed bacterial solution can be obtained;

[0040] (3) The mixed bacterial solution obtained in step 2 was centrifuged at 10,000 rpm at 4°C to obtain an extracellular polymer supernatant; after filtering through a 0.22 μm cellulose acetate membrane, it was purified using a dialysis membrane (3500 Da) at 4°C to remove the bacteria and impurities in the supernatant; methanol solution was then added and allowed to settle at 4°C, and centrifuged at 10,000 rpm at room temperature. The collected precipitate was freeze-dried to obtain the extracellular polymer of the mixed bacterial solution. The extracted extracellular polymer was mixed with Cu 2+Adding the final concentrations of 300 mg / L and 1 g / L to the mixed bacterial solution in step 2 to prepare a bioleaching agent;

[0041] (4) 1 g (10% W / V) of spent ternary lithium battery cathode material powder was added to a bioleaching agent and incubated for 3-7 days to obtain the bioleaching agent. Samples were taken daily and filtered through a 0.22 μm water filter. The concentrations of lithium, nickel, cobalt, and manganese in the leachate were measured using inductively coupled plasma optical emission spectroscopy (ICP-OES), and the extraction percentages were calculated.

[0042] The results showed that after 7 days of bioleaching, the leaching rate of lithium reached 99.9%, the leaching rate of nickel reached 92.3%, the leaching rate of cobalt reached 91.5%, and the leaching rate of manganese reached 94.1%.

[0043] Example 4

[0044] (1) After discharging, roasting, disassembling and grinding, the positive electrode material powder of the ternary lithium battery can be obtained;

[0045] (2) Add 22.1 g / L green vitriol, 5 g / L sulfur powder and 90 mL of 9K medium to a 250 mL conical flask, add 10 mL of a mixed bacterial solution of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans (the ratio of the added biomass is 3:2), and place in a constant temperature shaking incubator for cultivation at a temperature of 30°C and a rotation speed of 170 rpm. When the pH in the culture system is ≤1.2, the mixed bacterial solution can be obtained;

[0046] (3) The mixed bacterial solution obtained in step 2 was centrifuged at 10,000 rpm at 4°C to obtain an extracellular polymer supernatant; after filtering through a 0.22 μm cellulose acetate membrane, it was purified using a dialysis membrane (3500 Da) at 4°C to remove the bacteria and impurities in the supernatant; methanol solution was then added and allowed to settle at 4°C, and centrifuged at 10,000 rpm at room temperature. The collected precipitate was freeze-dried to obtain the extracellular polymer of the mixed bacterial solution. The extracted extracellular polymer was mixed with Cu 2+ Adding the final concentrations of 200 mg / L and 1 g / L to the mixed bacterial solution in step 2 to prepare a bioleaching agent;

[0047] (4) 0.8 g (8% W / V) of spent ternary lithium battery cathode material powder was added to a bioleaching agent and incubated for 3-7 days to obtain the bioleaching agent. Samples were taken daily and filtered through a 0.22 μm water filter. The concentrations of lithium, nickel, cobalt, and manganese in the leachate were measured using inductively coupled plasma optical emission spectroscopy (ICP-OES), and the extraction percentages were calculated.

[0048] The results showed that after seven days of bioleaching, the leaching rates of lithium, nickel, cobalt, and manganese all reached over 99%. This shows that the method of the present invention can effectively improve the bioleaching rate. Using the method of the present invention to bioleach waste ternary lithium-ion battery positive electrode materials can significantly increase the bioleaching rate of metal ions and shorten the leaching cycle.

Claims

1. Extracellular polymers and Cu 2+ The method for bioleaching of the positive electrode material of a ternary lithium battery with combined catalysis and retirement is characterized in that: The steps include: Step 1: Discharge, calcine and disassemble the waste ternary lithium battery to obtain ternary lithium positive electrode material powder; Step 2: Add Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans to the culture medium, and culture in a constant temperature shaking incubator at a temperature of 28-32° C. and a rotation speed of 150-200 rpm. When the pH of the culture system is ≤1.2, a mixed bacterial solution is obtained; Step 3: Extract extracellular polymers from the mixed bacterial solution obtained in step 2 and then 2+ At the same time, it is added to the mixed bacterial solution in step 2 to prepare a bioleaching agent; Step 4: Add the ternary lithium cathode material powder obtained in step 1 to the bioleaching agent prepared in step 3, react for 3-7 days, and obtain a bioleaching solution.

2. Extracellular polymers and Cu according to claim 1 2+ A method for bioleaching of cathode materials of ternary lithium batteries using combined catalysis and retirement is characterized in that The culture medium in step 2 is a modified 9K culture medium, consisting of 3 g / L (NH4)2SO4, 0.5 g / L KCl, 0.1 g / L K2HPO4, 0.5 g / L MgSO4·7H2O, 0.01 g / L Ca(NO3)2, 22.1 g / L green vitriol and 5 g / L sulfur powder.

3. Extracellular polymers and Cu according to claim 1 2+ A method for bioleaching of cathode materials of ternary lithium batteries using combined catalysis and retirement is characterized in that The biomass ratio of Thiobacillus ferrooxidans to Thiobacillus thiooxidans in the mixed bacterial solution of step 2 is 1:2 to 2:

1.

4. Extracellular polymers and Cu according to claim 1 2+ A method for bioleaching of cathode materials of ternary lithium batteries using combined catalysis and retirement is characterized in that The method for extracting extracellular polymers described in step 3 comprises the following specific steps: Thiobacillus ferrooxidans and Thiobacillus thiooxidans were mixed and cultured in a constant temperature shaking incubator until the pH was ≤ 1.2, and then centrifuged at 10,000 rpm and 4° C. to obtain an extracellular polymer supernatant; after filtering through a 0.22 μm cellulose acetate membrane, the supernatant was purified using a dialysis membrane (3,500 Da) at 4° C. to remove miscellaneous bacteria and impurities; a methanol solution was then added and allowed to stand at 4° C. for precipitation, and the mixture was centrifuged at 10,000 rpm and room temperature. The collected precipitate was freeze-dried to obtain the extracellular polymer of the mixed bacterial solution.

5. Extracellular polymers and Cu according to claim 1 2+ A method for bioleaching of cathode materials of ternary lithium batteries using combined catalysis and retirement is characterized in that The amount of extracellular polymer added in step 3 is 100-300 mg / L.

6. according to claim 1 extracellular polymers and Cu 2+ A method for bioleaching of cathode materials of ternary lithium batteries using combined catalysis and retirement is characterized in that Cu as described in step 3 2+ The addition amount is 0.8~1.2g / L.

7. according to claim 1 extracellular polymers and Cu 2+ A method for bioleaching of cathode materials of ternary lithium batteries using combined catalysis and retirement is characterized in that The addition amount of the ternary lithium battery positive electrode material powder in step 3 is 2-10% W / V.

Images