Method for co-processing sulfur-containing flue gas and waste lithium battery black powder

Abstract

The invention discloses a method for synergistically treating sulfur-containing flue gas and waste lithium battery black powder, which comprises the following steps: S1, compounding the waste lithium battery black powder with water and sulfuric acid to prepare black powder slurry A, carrying out gas-liquid two-phase full reaction on the black powder slurry A and the sulfur-containing flue gas in a desulfurizing tower to obtain desulfurized flue gas at the top of the tower and black powder slurry B at the bottom of the tower; s2, part of the nickel-cobalt-manganese-lithium powder is discharged to an acid leaching kettle to be subjected to acid leaching reaction operation, and a liquid-phase nickel-cobalt-manganese-lithium leaching solution and solid-phase coarse graphite slag are obtained after primary filter pressing; s3, adding the coarse graphite slag into a slag washing kettle, carrying out slag washing operation by using clear water, and carrying out secondary filter pressing to obtain pure graphite slag and slag washing liquid; and S4, compounding the slag washing liquid with newly added waste lithium battery black powder to prepare new black powder slurry A, and circulating the new black powder slurry A into the desulfurization tower for desulfurization operation. According to the preparation method disclosed by the invention, effective desulfurization of the sulfur-containing flue gas and efficient recovery of valuable metals in the waste lithium battery black powder are realized, the overall treatment cost is effectively reduced, and the environmental and economic benefits are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of resource recycling, and in particular to a method for co-processing sulfur-containing flue gas and waste lithium battery black powder. Background Art

[0002] With the transformation of the global energy structure and the booming development of the new energy vehicle industry, the market demand for lithium batteries, as a key power source, has shown explosive growth. Lithium batteries are not only widely used in portable electronic devices, but also play a vital role in electric vehicles and energy storage systems. However, the average service life of lithium batteries is limited, usually no more than 8 years, and the problem of handling a large number of retired lithium batteries has become increasingly prominent. These retired lithium batteries contain valuable metals such as nickel, cobalt, manganese, lithium, and copper. If they are not effectively recycled, they will not only cause a huge waste of resources, but also cause serious pollution to the environment, hindering the sustainable development of the industrial chain and the resource utilization of waste.

[0003] At present, the recycling process of retired lithium batteries is mainly divided into the steps of discharge, disassembly, crushing, and sorting. Through these processes, materials such as black powder, copper slag, aluminum slag, and diaphragms can be obtained. Among them, black powder contains high concentrations of metal elements such as nickel, cobalt, manganese, and lithium, and has a high recycling value. In the recycling process, black powder is usually mixed with an acidic solution and a reducing agent to leach sulfuric acid leaching solution containing nickel, cobalt, manganese, lithium, copper, and aluminum, and then the metal elements are recovered by different methods. In this process, commonly used reducing agents include hydrogen peroxide, sodium sulfite, and sodium metabisulfite.

[0004] The treatment of sulfur-containing flue gas is another important issue in the field of industrial desulfurization. The main components of these flue gases include nitrogen, oxygen, carbon dioxide, sulfur dioxide, sulfur trioxide, hydrofluoric acid, hydrogen chloride, etc., which pose a threat to the environment and human health. Traditional flue gas desulfurization technology mainly uses alkaline reagents such as limestone or calcium oxide for absorption, removes sulfur by generating calcium sulfite and calcium sulfate, and finally discharges it in the form of gypsum slag. Although this method can effectively remove sulfur, it will produce a large amount of desulfurization wastewater and gypsum slag, causing secondary pollution and waste of resources.

[0005] CN101185830 A discloses a limestone-gypsum flue gas desulfurization process, which uses organic acid to dissolve limestone, absorbs sulfur dioxide, and oxidizes the generated calcium sulfite into hydrated gypsum. CN102162034 A discloses a process for recovering valuable metals from waste batteries, which uses sulfuric acid and hydrogen peroxide for acid leaching reaction, uses hydrogen peroxide as a reducing agent, and obtains a leachate containing metal elements.

[0006] In summary, although the existing lithium battery recycling and flue gas desulfurization technologies have solved the problems of resource recovery and environmental pollution to a certain extent, they still have shortcomings such as low efficiency, high cost, and secondary pollution. Therefore, the development of a new type of coordinated processing technology that is both economical and environmentally friendly is of great significance for improving the recycling rate of lithium batteries, reducing environmental pollution, and promoting resource recycling. Summary of the invention

[0007] In view of the above shortcomings of the prior art, the present invention provides a method for the coordinated treatment of sulfur-containing flue gas and waste lithium battery black powder to solve the technical problems of high cost, low efficiency, serious secondary pollution, difficulty in treating waste lithium battery black powder, and low resource recovery rate in the traditional desulfurization process. Through the method of the present invention, effective desulfurization of sulfur-containing flue gas and efficient recovery of valuable metals in waste lithium battery black powder are achieved, while reducing the overall treatment cost, improving environmental and economic benefits, and demonstrating a new environmentally friendly, economical and efficient coordinated treatment technology.

[0008] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0009] A method for co-processing sulfur-containing flue gas and waste lithium battery black powder, the method comprising the following steps:

[0010] S1: taking a certain amount of waste lithium battery black powder and mixing it with water and sulfuric acid to prepare black powder slurry A, and subjecting the black powder slurry A to a full gas-liquid two-phase reaction with sulfur-containing flue gas in a desulfurization tower, obtaining desulfurized flue gas after at least sulfur dioxide gas in the flue gas is removed at the top of the desulfurization tower, and obtaining black powder slurry B at the bottom of the tower;

[0011] S2: Part of the black powder slurry B obtained in step S1 is circulated into the desulfurization tower, and part of it is discharged to the acid leaching kettle, a small amount of sulfuric acid solution is added to the acid leaching kettle to carry out an acid leaching reaction operation of the black powder slurry B, and then after a pressure filtration, a liquid nickel-cobalt-manganese-lithium leaching solution and a solid coarse graphite slag are obtained;

[0012] S3: adding the coarse graphite slag obtained in step S2 into a slag washing kettle, washing the slag with clean water, and then performing secondary filter pressing to obtain pure graphite slag and slag washing liquid;

[0013] S4: the slag washing liquid obtained in step S3 is compounded with the newly added waste lithium battery black powder in a batching kettle to prepare a new black powder slurry A, which is circulated to the desulfurization tower for desulfurization operation.

[0014] As a preferred technical solution, the desulfurized flue gas obtained in step S1 is transported to the bottom of the tail gas absorption tower, and the tail gas is absorbed by the sodium carbonate solution sprayed into the top of the tail gas absorption tower. After sulfur dioxide is further removed from the desulfurized flue gas, it is discharged from the top of the tail gas absorption tower, and a sodium sulfite solution is obtained at the bottom of the tower.

[0015] As a preferred technical solution, the sodium sulfite solution is circulated into the acid leaching kettle as a reducing agent to convert the high-valent nickel-cobalt-manganese compounds in the waste lithium battery black powder into low-valent nickel-cobalt-manganese metal compounds, which has very good environmental and economic benefits.

[0016] As a preferred technical solution, the waste lithium battery black powder is the positive and negative electrode black powder of the waste lithium battery after being disassembled, crushed, and separated into copper powder and aluminum powder.

[0017] As a preferred technical solution, the waste lithium battery is at least one of a lithium cobalt oxide battery, a nickel-cobalt-manganese ternary lithium battery, and a lithium manganese oxide battery.

[0018] As a preferred technical solution, the sulfur-containing flue gas is first subjected to a dust removal and cooling pretreatment operation.

[0019] As a preferred technical solution, the sulfur-containing flue gas also contains waste gases such as hydrogen chloride, hydrogen fluoride, nitrogen oxides and sulfur trioxide.

[0020] As a preferred technical solution, in step S1, the solid-liquid ratio of the waste lithium battery black powder to water is 1:3-5, and the amount of sulfuric acid added is 20-50% of the mass of the waste lithium battery black powder.

[0021] As a preferred technical solution, the pH of the reaction solution in the acid leaching kettle is controlled to be 1-2, and the reaction temperature is 50-80°C.

[0022] As a preferred technical solution, in step S4, the solid-liquid ratio of the slag washing liquid to the waste lithium battery black powder is 1:3-5.

[0023] Beneficial effects of the present invention:

[0024] The method for synergistically treating sulfur-containing flue gas and waste lithium battery black powder of the present invention uses waste lithium battery black powder as a desulfurization and denitrification agent for sulfur-containing flue gas, and uses waste lithium battery black powder to absorb and remove hydrogen fluoride, hydrogen chloride, nitrogen oxides, sulfur dioxide, and sulfur trioxide gases therein; the generated hydrochloric acid, nitric acid, and sulfuric acid can be used as acids for leaching waste lithium battery black powder, and sulfur dioxide can be used to reduce high-priced nickel-cobalt-manganese compounds in waste lithium battery black powder to low-priced nickel-cobalt-manganese metal compounds, which are more suitable for reacting with sulfuric acid to generate nickel-cobalt-manganese sulfate. The waste lithium battery black powder slurry at the bottom of the tower that absorbs this mixed gas enters the acid leaching kettle again, and a certain amount of sulfuric acid is added to leach the nickel-cobalt-manganese-lithium oxygen metal elements in the waste lithium battery black powder to obtain a nickel-cobalt-manganese-lithium mixed sulfate solution. The two purposes of sulfuric acid leaching of waste lithium batteries and flue gas desulfurization are achieved through this process. It not only reduces the cost required for flue gas treatment, but also saves the amount of reducing agent and sulfuric acid required for sulfuric acid leaching of black powder.

[0025] In general, the present invention makes full use of the synergistic effect of sulfur-containing flue gas and waste lithium battery black powder, which not only improves the resource utilization rate of waste lithium battery black powder and reduces the risk of environmental pollution, but also significantly reduces the overall processing cost of sulfur-containing flue gas and waste lithium battery black powder by reducing the use of chemicals and optimizing the process flow, thereby enhancing the economic benefits of the operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The process flow chart of the pilot test stage of Example 1 of the present invention is shown in FIG. DETAILED DESCRIPTION

[0027] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art may think of other obvious variations.

[0028] Example 1

[0029] The method for co-processing sulfur-containing flue gas and waste lithium batteries in this embodiment is as follows: Figure 1 The process flow chart of the pilot test stage shown in the figure specifically includes the following steps:

[0030] S1: Prepare the reaction device for the test. In order to improve the utilization rate of sulfur dioxide, this test is carried out in series with two desulfurization towers. Take two 500ml conical flasks, find two rubber stoppers that can just plug the conical bottle mouths, make two holes on the rubber stoppers, and insert a glass tube into each. One of the glass tubes extends 5-7cm below the liquid surface as the air inlet pipe. The other glass tube is flush with the rubber stopper as the air outlet pipe. Use a 250ml conical flask, a separatory funnel, a rubber stopper and a glass tube to combine into a sulfur dioxide gas generator. The outlet glass tube mouth is connected to the air inlet of a micro duct fan with a rubber hose, and the outlet of the duct fan is transferred to the 1# conical flask (i.e. Figure 1 The gas inlet glass tube of the desulfurization tower shown in FIG. 1 is connected to the gas outlet glass tube of the 1# conical bottle by a rubber hose to the 2# conical bottle (i.e. Figure 1 The gas inlet glass tube of the desulfurization tower shown in the figure is connected to a self-made tail gas absorption device (i.e. Figure 1 100g of 5% sodium carbonate solution was added to the device to absorb the unreacted sulfur dioxide gas to obtain a sodium sulfite solution. The air tightness was checked before use to ensure that there was no leakage of sulfur dioxide gas during the test.

[0031] S2: Take 100g each of waste lithium battery black powder (the waste lithium battery black powder is the positive and negative electrode black powder after the waste lithium battery is disassembled, crushed, and the copper powder and aluminum powder are separated, specifically the positive electrode material and negative electrode mixed black powder recovered from waste nickel-cobalt-manganese ternary lithium batteries, and its composition is shown in Table 1) and add it to two 500ml conical flasks (i.e. Figure 1 In the batching kettle shown in the figure, add 300 ml of water to each, put in a magnetic stirring rotor, place it on a magnetic stirrer for stirring, and the stirring speed is 100 rpm. Slowly add 40 g of sulfuric acid, mix and slurry for 30 minutes to make black powder slurry A. In the absence of sulfur dioxide gas, the metal copper and aluminum in the nickel-cobalt-manganese battery black powder react with sulfuric acid to produce the corresponding sulfate, and then in two conical flasks (at this time it is converted into Figure 1 The sulfur dioxide inlet and outlet pipelines are connected to the desulfurization tower shown in the figure, and the desulfurization test of waste lithium battery black powder is started.

[0032] Table 1 Black powder composition test table of waste lithium batteries element Ni Co Mn Li Cu Al content% 2.45 17.49 11.76 4.14 1.02 1.56

[0033] S3: Weigh 35g of sodium bisulfite and add it to a 250ml conical flask, connect the pipeline, add 90ml of 20% concentrated sulfuric acid to the separatory funnel, slowly add sulfuric acid at a rate of 1ml / min, and the generated sulfur dioxide enters the 1# conical flask (i.e. Figure 1 In the desulfurization tower shown in FIG, sulfuric acid is added at a rate of 1 ml / min, and sulfur dioxide gas enters the conical flask used for the reaction (i.e. Figure 1 In the desulfurization tower shown in the figure, the magnetic stirrer is turned on for stirring and heating, the heating temperature is controlled at 80°C, the sulfuric acid is added for 90 minutes, and stirring is continued for 5 minutes after the addition is completed. The stirring is stopped and the air pipe is removed. At this time, the waste battery black powder in the 1# conical bottle is converted into black powder slurry B obtained in the desulfurization tower.

[0034] S4: To 1# conical flask (this is equivalent to Figure 1 A small amount of concentrated sulfuric acid is added to the reaction liquid in the leaching kettle shown in the figure, the pH of the reaction liquid is controlled to 2, and the leaching is stirred again, the stirring speed is 100 rpm, the reaction temperature is 60°C, the reaction time is 90 min, a small sample is taken for filtration and separation, and the graphite slag is washed with water to obtain the graphite slag, and the contents of nickel, cobalt and manganese in the graphite slag are detected. When the contents of nickel, cobalt and manganese in the graphite slag are <0.015%, the stirring is stopped, otherwise the reaction is stirred again until the nickel, cobalt and manganese in the small sample are qualified.

[0035] S5: The leached liquid is filtered (the filtering method is not particularly limited, for example, a filter press can be used), and then the filter residue is washed with a small amount of clean water, and the washing liquid is combined to obtain 1# sulfuric acid leaching solution (i.e. Figure 1 500ml of nickel-cobalt-manganese-lithium leaching solution, filter residue (i.e. Figure 1 The crude graphite slag in the slag washing kettle is then slurried and rinsed with water, with a solid-liquid ratio of 1:3. The filter is filtered by a filter press method and then the filter residue is washed with water to obtain 1# wet graphite slag (i.e. Figure 138g of pure graphite slag in the ternary black powder) and slag washing liquid, which can be compounded with waste lithium battery black powder in the batching kettle to form black powder slurry A for recycling. Samples are taken to detect the nickel, cobalt, manganese, copper, aluminum and lithium contents in the sulfuric acid leaching solution and the 1# wet graphite slag. The leaching rate of each metal element is calculated based on the amount of metal in the ternary black powder and the amount of metal in the leached graphite slag. The test data summary calculation table is shown in Table 2.

[0036] Table 2 Summary of test data element Ni Co Mn Li Cu Al Leachate g / L 4.66 33.23 22.35 7.94 1.88 2.96 Graphite slag, % 0.017 0.037 0.034 0.001 0.0008 0.001 Leaching rate% 99.74 99.93 99.95 99.99 99.97 99.98

[0037] The chemical reaction equation for the above process is as follows:

[0038] 2LiMO2+Cu+4H2SO4=Li2SO4+2MSO4+CuSO4+4H2O

[0039] 6LiMO2+2Al+12H2SO4=3Li2SO4+6MSO4+Al2(SO4)3+12H2O

[0040] 2LiMO2+SO2+2H2SO4=Li2SO4+2MSO4+2H2O

[0041] M: Ni, Mn, Co and other elements

[0042] 2Al+3H2SO4=Al2(SO4)3+3H2

[0043] 2NaHSO3+H2SO4=Na2SO4+2SO2↑+2H2O;

[0044] S6: The sulfite content in the sodium bisulfite sampled and tested was 69.38%, the sulfite content in the tail gas absorption liquid sampled and tested was 0.031%, the amount of sulfite in the absorption liquid was 0.031g, and the amount of sulfite added was 31.221g. The utilization rate of the sodium sulfite in this test was calculated to be 99.90%.

[0045] Comparative Example 1

[0046] This comparative example provides a sulfuric acid leaching method for waste lithium battery black powder. The sulfuric acid leaching test without introducing sulfur dioxide comprises the following steps:

[0047] S1: Take 100g of waste lithium battery black powder into a 500ml conical flask, add 300ml of water, stir at 100 rpm, add 118g of sulfuric acid (125% of the theoretical amount), maintain the reaction temperature at 80°C, and react for 150min.

[0048] S2: Stop stirring, filter the reaction liquid in the beaker, rinse the filter residue with a small amount of clean water, combine the washing liquid, and obtain 500ml of 2# sulfuric acid leaching solution. Add water to the filter residue for pulping and rinsing, with a solid-liquid ratio of 1:3. After filtering, wash the filter residue with water to obtain 53g of 2# graphite slag. Take samples to detect the nickel, cobalt, manganese, copper, aluminum and lithium content in the sulfuric acid leaching solution and the graphite slag. Calculate the leaching rate of metal elements based on the amount of metal in the input waste lithium battery black powder and the amount of metal in the leached graphite slag. See Table 3 for the summary calculation table of test data.

[0049] Table 3 Test data summary element Ni Co Mn Li Cu Al Leachate g / L 4.65 22.02 15.30 7.42 1.89 2.95 Graphite slag, % 0.014 8.04 7.15 0.74 0.0007 0.0006 Leaching rate% 99.70 63.76 67.78 90.53 99.96 99.98

[0050] The experimental results show that through comparative example 1, it is explained that in the sulfuric acid leaching process of the waste nickel-cobalt-manganese battery black powder, when a large amount of sulfuric acid is added (28g more is added), the overall leaching rate of nickel-cobalt-manganese-lithium is still lower than that of Example 1. The high-valent nickel, cobalt and manganese compounds are difficult to react with sulfuric acid, while the copper and aluminum metals can react with sulfuric acid and be used as reducing agents. The leaching rates of copper and aluminum are not much different.

[0051] The chemical reaction equation for the above process is as follows:

[0052] 2Al+3H2SO4=Al2(SO4)3+3H2

[0053] 2LiMO2+Cu+4H2SO4=Li2SO4+2MSO4+CuSO4+4H2O

[0054] 6LiMO2+2Al+12H2SO4=3Li2SO4+6MSO4+Al2(SO4)3+12H2O

[0055] 2LiMO2+3H2SO4=Li2SO4+2MSO4+3H2O+0.5O2

[0056] M: elements such as Ni, Mn, and Co.

[0057] Comparative Example 2

[0058] This comparative example provides a sulfuric acid leaching method for waste lithium battery black powder, and the sulfuric acid leaching test under the condition of adding sodium bisulfite comprises the following steps:

[0059] S1: Take 100g of waste nickel-cobalt-manganese ternary lithium battery black powder into a 500ml conical flask, add 300ml of water, stir at 100 rpm, add 118g of sulfuric acid (125% of the theoretical amount), stir and react for 30min, then add 45g of sodium bisulfite in batches. In order to improve the utilization rate of sodium bisulfite and less volatilize sulfur dioxide gas in the acidic liquid, add 1g of sodium bisulfite every 2min, keep the reaction temperature at 80°C, and the total reaction time is 150min.

[0060] S2: Stop stirring, filter the reaction liquid in the beaker, and then rinse the filter residue with a small amount of clean water to obtain 500ml of 3# sulfuric acid leaching solution. Add water to the filter residue for pulping and rinsing, with a solid-liquid ratio of 1:3. After filtering, wash the filter residue with water, combine the washing liquid, and obtain 40g of 3# graphite slag. Take samples to detect the nickel, cobalt, manganese, copper, aluminum and lithium content in the sulfuric acid leaching solution and the graphite slag. Calculate the leaching rate of metal elements based on the amount of metal in the ternary black powder and the amount of metal in the leached graphite slag. See Table 4 for the summary calculation table of test data.

[0061] Table 4 Summary of test data element Ni Co Mn Li Cu Al Leachate g / L 4.65 31.02 22.30 7.86 1.88 2.95 Graphite slag, % 0.011 3.73 0.24 0.14 0.0007 0.0008 Leaching rate% 99.82 91.47 99.18 98.65 99.97 99.98

[0062] The chemical reaction equation for the above process is as follows:

[0063] 2Al+3H2SO4=Al2(SO4)3+3H2

[0064] 2LiMO2+Cu+4H2SO4=Li2SO4+2MSO4+CuSO4+4H2O

[0065] 6LiMO2+2Al+12H2SO4=3Li2SO4+6MSO4+Al2(SO4)3+12H2O

[0066] 2LiMO2+3H2SO4=Li2SO4+2MSO4+3H2O+0.5O2

[0067] 4LiMO2+2NaHSO3+5H2SO4=2Li2SO4+4MSO4+Na2SO4+6H2O

[0068] M: elements such as Ni, Mn, and Co.

[0069] Comparative Examples 1 and 2 show that in the sulfuric acid leaching process of the waste lithium battery black powder, the sulfuric acid leaching rate of cobalt and manganese is greatly improved when sodium bisulfite is used as a reducing agent compared with the case without a reducing agent. However, the amount of sulfuric acid used is 28g more than that in Example 1.

[0070] The method of the invention uses waste lithium battery black powder as a desulfurizing agent for sulfur-containing flue gas, does not use conventional methods for desulfurization, but uses waste lithium battery black powder to absorb and remove hydrogen fluoride, hydrogen chloride, nitrogen oxides, sulfur dioxide and sulfur trioxide mixed gas therein; hydrogen fluoride, hydrogen chloride, sulfur trioxide and nitrogen oxides can be dissolved in water to form acid, thereby reducing the amount of sulfuric acid used when leaching the waste lithium battery black powder; sulfur dioxide gas is used as a reducing agent to reduce high-valence nickel-cobalt-manganese oxides in the waste lithium battery black powder to low-valence nickel-cobalt-manganese oxides, making it easier to leach nickel-cobalt-manganese-lithium mixed sulfuric acid solution when subsequent sulfuric acid leaches the waste lithium battery black powder, thereby achieving multiple purposes of flue gas desulfurization and reduction leaching of waste lithium battery black powder for coordinated treatment. Conventional desulfurization with limestone or calcium oxide will produce a large amount of desulfurization wastewater and a large amount of gypsum slag; now using waste lithium battery black powder as a desulfurizer, there is no problem of difficult treatment of desulfurization wastewater and gypsum slag; the present invention improves the leaching rate of nickel, cobalt, manganese and lithium elements of waste lithium battery black powder by combining a desulfurization tower and an externally discharged acid leaching kettle, so that the nickel, cobalt, manganese and lithium sulfate solution obtained by leaching can be subsequently recycled. In addition, the series process of the desulfurization tower and the tail gas absorption tower can further improve the absorption rate of sulfur dioxide, and the trace sulfur dioxide and unreacted carbon dioxide in the tail gas are discharged after the sulfur dioxide is absorbed by the alkali absorption tower.

[0071] In general, the collaborative treatment method of the present invention is simple and easy to implement, low-cost, and can achieve economic benefits while eliminating environmental pollution factors, thereby having good social benefits.

[0072] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention, and these changes and improvements fall within the scope of the present invention claimed.

Claims

1. A method for the coordinated treatment of sulfur-containing flue gas and waste lithium battery black powder, characterized in that: The method comprises the following steps: S1: taking a certain amount of waste lithium battery black powder and mixing it with water and sulfuric acid to prepare black powder slurry A, and subjecting the black powder slurry A to a full gas-liquid two-phase reaction with sulfur-containing flue gas in a desulfurization tower, obtaining desulfurized flue gas after at least sulfur dioxide gas in the flue gas is removed at the top of the desulfurization tower, and obtaining black powder slurry B at the bottom of the tower; S2: Part of the black powder slurry B obtained in step S1 is circulated into the desulfurization tower, and part of it is discharged to the acid leaching kettle, a small amount of sulfuric acid solution is added to the acid leaching kettle to carry out an acid leaching reaction operation of the black powder slurry B, and then after a pressure filtration, a liquid nickel-cobalt-manganese-lithium leaching solution and a solid coarse graphite slag are obtained; S3: adding the coarse graphite slag obtained in step S2 into a slag washing kettle, washing the slag with clean water, and then performing secondary filter pressing to obtain pure graphite slag and slag washing liquid; S4: the slag washing liquid obtained in step S3 is compounded with the newly added waste lithium battery black powder in a batching kettle to prepare a new black powder slurry A, which is circulated to the desulfurization tower for desulfurization operation.

2. The method for co-processing sulfur-containing flue gas and waste lithium battery black powder as claimed in claim 1, characterized in that: The desulfurized flue gas obtained in step S1 is transported to the bottom of the tail gas absorption tower, and the tail gas is absorbed by the sodium carbonate solution sprayed into the top of the tail gas absorption tower. After sulfur dioxide is further removed from the desulfurized flue gas, it is discharged from the top of the tail gas absorption tower, and a sodium sulfite solution is obtained at the bottom of the tower.

3. The method for co-processing sulfur-containing flue gas and waste lithium battery black powder as claimed in claim 2, characterized in that: The sodium sulfite solution is circulated into the acid leaching kettle as a reducing agent to convert the high-valent nickel-cobalt-manganese compounds in the waste lithium battery black powder into low-valent nickel-cobalt-manganese metal compounds.

4. The method for co-processing sulfur-containing flue gas and waste lithium battery black powder according to claim 1, characterized in that: The waste lithium battery black powder is the positive and negative electrode black powder obtained by disassembling, crushing and separating the copper powder and the aluminum powder of the waste lithium battery.

5. The method for co-processing sulfur-containing flue gas and waste lithium battery black powder as claimed in claim 1, characterized in that: The waste lithium battery is at least one of a lithium cobalt oxide battery, a nickel-cobalt-manganese ternary lithium battery, and a lithium manganese oxide battery.

6. The method for co-processing sulfur-containing flue gas and waste lithium battery black powder as claimed in claim 1, characterized in that: The sulfur-containing flue gas is first subjected to a dust removal and cooling pretreatment operation.

7. The method for co-processing sulfur-containing flue gas and waste lithium battery black powder as claimed in claim 1, characterized in that: The sulfur-containing flue gas also contains waste gases such as hydrogen chloride, hydrogen fluoride, nitrogen oxides and sulfur trioxide.

8. The method for co-processing sulfur-containing flue gas and waste lithium battery black powder as claimed in claim 1, characterized in that: In step S1, the solid-liquid ratio of the waste lithium battery black powder to water is 1:3-5, and the amount of sulfuric acid added is 20-50% of the mass of the waste lithium battery black powder.

9. The method for co-processing sulfur-containing flue gas and waste lithium battery black powder as claimed in claim 1, characterized in that: The pH of the reaction solution in the acid leaching kettle is controlled to be 1-2, and the reaction temperature is 50-80°C.

10. The method for co-processing sulfur-containing flue gas and waste lithium battery black powder according to claim 1, characterized in that: In step S4, the solid-liquid ratio of the slag washing liquid to the waste lithium battery black powder is 1:3-5.

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