Method for removing phosphorus from extraction wastewater in hydrometallurgy industry

Abstract

Provided in the present disclosure is a method for removing phosphorus from extraction wastewater in the hydrometallurgy industry. The method comprises the following steps: S1, adjusting the pH of extraction wastewater to 3.5-4.5, adding ferrous sulfate thereto, and then carrying out an ultrasonic treatment to obtain a suspension; S2, carrying out solid-liquid separation on the suspension, taking out the liquid phase, stirring same, adding an acid solution to adjust the pH to 3-3.5, then adding ferrous sulfate and hydrogen peroxide, introducing oxygen and pressurizing same, and heating same to perform a reaction; S3, adding an alkaline solution thereto to adjust the pH to 7.5-8, then sequentially adding a coagulant and a flocculant thereto, carrying out solid-liquid separation, then taking out the liquid phase, adjusting the pH to 6-7, carrying out ozonation, adding aluminum sulfate after the reaction is finished, carrying out solid-liquid separation, and then measuring the phosphorus content of the effluent.

Description

A method for removing phosphorus from extraction wastewater in the hydrometallurgical industry Technical Field

[0001] The present invention belongs to the technical field of wastewater treatment, and particularly relates to a method for removing phosphorus from extraction wastewater in the hydrometallurgical industry. Background Art

[0002] my country's new energy electric vehicle industry is developing rapidly, and the demand for power batteries is increasing. This has led to the generation of a large number of waste batteries. Waste batteries contain a wide variety of rare and precious metals, with high content, and have great recycling value.

[0003] In the process of recovering valuable metals such as nickel, cobalt, and manganese from spent lithium-ion battery cathode materials, solvent extraction is typically used to concentrate, purify, and remove impurities from the cathode material leachate. Solvent extraction involves mixing two immiscible or slightly soluble solvents (aqueous and organic) to transfer the solute from one solvent to the other (from the aqueous phase to the organic phase or vice versa). The organic phase consists of an extractant and a diluent, typically sulfonated kerosene. The most commonly used extractants are acidic phosphorus extractants, such as P204 (di(2-ethylhexyl) phosphate), which is commonly used for extracting aluminum and manganese, P507 (mono-2-ethylhexyl 2-ethylhexylphosphonate), which is commonly used for complete extraction of nickel, cobalt, and manganese, and C272 (di(2,4,4)trimethylpentylphosphinic acid) for selective extraction of cobalt or nickel-magnesium separation. Although the organic phase is composed of poorly soluble and difficult-to-degrade organic substances, in actual production, due to the large solution processing volume and limited stirring and separation time, the organic phase is inevitably entrained in the aqueous phase. In particular, after saponification, the organic phase becomes more hydrophilic, resulting in incomplete phase separation. Some organic matter is carried over into the stripping liquid and raffinate, leading to significant loss of extraction agent and increased production costs. In addition, these oily substances can affect subsequent product quality and wastewater discharge, necessitating oil-water separation.

[0004] Summary of the Invention

[0005] The present invention addresses the problem of difficulty in removing phosphorus from extraction wastewater during the recycling process of retired lithium-ion batteries, and proposes a method for removing phosphorus from extraction wastewater in the hydrometallurgical industry.

[0006] According to a first aspect of the present disclosure, a method for removing phosphorus from extraction wastewater in the hydrometallurgical industry is proposed, comprising the following steps:

[0007] S1: The pH of the extraction wastewater is adjusted to 3.5-4.5, ferrous sulfate is added, and ultrasonic treatment is performed to obtain a suspension;

[0008] S2: separating the suspension into solid and liquid, taking the liquid phase and stirring it, adding acid to adjust the pH to 3-3.5, adding ferrous sulfate and hydrogen peroxide, introducing oxygen to increase pressure, and heating the reaction;

[0009] S3: After adding alkaline solution to adjust the pH to 7.5-8, coagulant and flocculant are added in sequence, solid-liquid separation is performed, pH is adjusted to 6-7, ozone oxidation is performed, aluminum sulfate is added after the reaction is completed, and the water phosphorus content is detected after solid-liquid separation.

[0010] In step S1, the pH of the extracted wastewater is adjusted to 4 to reduce the solubility of the extractant, and at the same time facilitates the subsequent adjustment of the pH of the Fenton inlet to 3-3.5; in step S2, the acid solution is added to adjust the pH of the liquid phase to meet the pH requirements of the Fenton inlet; in step S3, the alkali solution is added to adjust the pH to 7.5-8 to remove Fe 3+ , Fe 3+ It will react with inorganic phosphorus to produce precipitation, further reducing the phosphorus content in the solution.

[0011] In some embodiments, in step S1, the solid-to-liquid ratio of the ferrous sulfate to the extraction wastewater is 0.001 to 0.01 g / mL. Adding ferrous sulfate can reduce the solubility of the extractant.

[0012] In some embodiments, in step S1, the ultrasonic treatment is performed at 30-40°C; and / or the ultrasonic treatment frequency is 35-40 kHz; and / or the ultrasonic treatment duration is 0.5-1 hour. Ultrasonic treatment has the effect of demulsification and oil removal, and better results can be achieved within this parameter range.

[0013] In some embodiments, in step S2, the stirring speed is 100-300 rpm.

[0014] In some embodiments, in step S2, the molar ratio of ferrous sulfate to hydrogen peroxide is 1:(3-10).

[0015] In some embodiments, in step S2, the concentration of the hydrogen peroxide is 27.5% to 35%; and / or the mass ratio of the hydrogen peroxide to the COD of the extraction wastewater is (1-2):1.

[0016] In some embodiments, in step S2, the oxygen is introduced to pressurize the solution so as to reach a pressure of 0.2 to 0.5 MPa.

[0017] In some embodiments, in step S2, the temperature-elevated reaction is a two-stage reaction; wherein the temperature of the first stage is 30-40°C and the reaction time is 2-3 hours; and the temperature of the second stage is 120-150°C and the reaction time is 1-2 hours. Under the conditions of the first stage reaction, the extractant (organophosphate) in the extraction wastewater is mostly oxidized to small molecules, and a small portion is directly oxidized to inorganic phosphorus; under the conditions of the second stage reaction, the remaining extractant and small molecules are further oxidized to inorganic phosphorus.

[0018] In some embodiments, the first-stage reaction is a Fenton oxidation reaction, and the second-stage reaction is a wet catalytic oxidation reaction. In the Fenton oxidation reaction, ferrous sulfate reacts with hydrogen peroxide to generate hydroxyl radicals, which can oxidize the extractant into small molecules. In the wet catalytic oxidation reaction, the extractant can be decomposed into inorganic phosphorus under high temperature and high pressure.

[0019] In some embodiments, in step S2, the temperature-elevated reaction further comprises a stirring step, and the stirring speeds of the first-stage reaction and the second-stage reaction are independently selected from 400 to 600 rpm.

[0020] In some embodiments, in step S3, the cooling is to reduce the temperature of the reaction solution to 20-25°C.

[0021] In some embodiments, in step S3, the reaction solution is stirred after cooling, and the stirring speed is 100 to 300 rpm.

[0022] In some embodiments, in step S3, the coagulant is polyaluminium chloride (PAC), and the polyaluminium chloride is added to a concentration of 200 to 300 ppm. Polyaluminium oxide is used to precipitate inorganic phosphorus.

[0023] In some embodiments, the basicity of the polyaluminium chloride is 60% to 80%. The polyaluminium chloride has good flocculation and sedimentation effects.

[0024] In some embodiments, in step S3, the flocculant is polyacrylamide (PAM); and / or the molecular weight of the PAM is about 1200W; and / or the amount of the PAM added is 3-5 ppm. Using this amount of flocculant can save costs and facilitate subsequent flocculation, sedimentation, and filtration.

[0025] In some embodiments, in step S3, the ozone oxidation is performed using activated carbon loaded with metal oxides as a catalyst. The activated carbon adsorbs the extractant on its surface, and the metal oxides loaded on the activated carbon act as a catalyst to decompose the extractant by ozone oxidation.

[0026] In some embodiments, the metal oxide is at least one of titanium dioxide, copper oxide, or manganese dioxide. The ozone catalyst concentrates the extractant on its surface, and ozone is more likely to generate hydroxyl radicals on the surface of the catalyst metal oxide, thereby improving the ozone oxidation efficiency.

[0027] In some embodiments, in step S3, the ozone oxidation is performed in an ozone catalytic oxidation reactor; the catalyst is filled at a level of 50% to 60% of the reactor's height. The volume of the solution in the reactor expands when ozone is introduced, and a 40% to 50% safety margin for expansion is required.

[0028] In some embodiments, in step S3, the ozone oxidation time is 10 to 30 minutes. After the ozone oxidation process, most of the remaining extractant has been oxidized and decomposed.

[0029] In some embodiments, in step S3, the amount of aluminum sulfate added is 50 to 200 ppm. Aluminum sulfate is acidic in nature and will continuously hydrolyze due to the neutral pH of the sewage, generating a polynuclear carboxyl complex that reacts with orthophosphate in the water to form a phosphate precipitate, thereby achieving the effect of phosphorus removal.

[0030] In some embodiments, in step S3, after the ozone oxidation reaction is completed, the tail gas enters the ozone decomposition device.

[0031] The principle of the removal method described in the first aspect of the present disclosure is as follows: the Fenton reaction partially oxidizes the extractant (organophosphate) into inorganic phosphorus and small molecules, and the wet catalytic oxidation reaction further oxidizes the extractant and small molecules into inorganic phosphorus. Polyaluminum chloride is then added to remove the oxidized inorganic phosphorus, and a coagulant (such as PAC) and a flocculant (such as PAM) are added in sequence to facilitate filtration. The remaining extractant in the solution is adsorbed by the ozone catalyst, and an oxidation reaction occurs with ozone on the catalyst surface to decompose the extractant into inorganic phosphorus. Finally, aluminum sulfate is added to precipitate the inorganic phosphorus to achieve the phosphorus removal effect.

[0032] According to a second aspect of the present disclosure, a method for recycling lithium batteries is provided, comprising the steps of the method for removing phosphorus from extraction wastewater in the hydrometallurgical industry as described in the first aspect of the present disclosure. The method for recycling lithium batteries, comprising the method described in the first aspect of the present disclosure, can effectively remove organic phosphines from the extraction wastewater, making the lithium battery recycling method more environmentally friendly.

[0033] According to one embodiment of the present disclosure, there are at least the following beneficial effects:

[0034] (1) The present invention reduces the hydrophilicity of the extractant by first adding ferrous sulfate, solidifies part of the oil, and then converts the dispersed oil and emulsified oil (W / O) / (O / W) in the extraction wastewater into suspended oil by ultrasonic wave for removal, and oxidizes and removes the extractant by wet catalytic oxidation. Adding oxygen during the wet catalytic oxidation process can increase the pressure and inhibit the decomposition of hydrogen peroxide to a certain extent, increase the reaction rate, and the orthophosphate decomposed by the extractant reacts with the Fe in the solution. 3+ Directly generate precipitation, reducing the subsequent addition of phosphorus removal agents.

[0035] (2) The back-end of the disclosed process uses an activated carbon-containing catalyst to perform ozone catalytic oxidation to deeply remove the undecomposed extractant. The phosphorus removal rate can reach over 97% using the disclosed method. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present disclosure is further described below with reference to the accompanying drawings and embodiments, wherein:

[0037] FIG1 is a flow chart of a method for removing phosphorus from extraction wastewater in the hydrometallurgical industry according to Example 1 of the present disclosure. DETAILED DESCRIPTION

[0038] The following examples clearly and completely describe the concepts and technical effects of this disclosure, in conjunction with the following examples, to provide a full understanding of the objectives, features, and effects of this disclosure. The wastewater used in the examples and comparative examples is extraction wastewater from the ternary battery recycling industry; PAM is 1200 nonionic polyacrylamide; PAC and PAM are both analytical grade reagents; and the activated carbon-supported catalyst is RHCY03.

[0039] Example 1

[0040] A method for removing organic phosphorus from extraction wastewater in the hydrometallurgical industry, as shown in FIG1 , comprises the following specific steps:

[0041] (1) Take 1.5 L of sodium saponification wastewater (oil content is 39 mg / L, COD is 18000 mg / L, P is 417 mg / L) in a beaker, adjust the pH to 4, add 15 g of ferrous sulfate, place the beaker in an ultrasonic cleaning machine, set the temperature to 40 ° C, and the reaction time is 1 h to demulsify and remove oil.

[0042] (2) Remove the beaker and remove the solidified oil and precipitate on the water surface. Place the beaker on a magnetic stirrer, add a stirring magnet, adjust the speed to 200 rpm, and continue stirring. Detect the COD value at this time. Simultaneously, add sulfuric acid dropwise to the deoiled saponified water. Monitor the pH value of the solution in real time with a pH meter while stirring until the pH of the solution is adjusted to 3. Then, add 45 g of ferrous sulfate heptahydrate.

[0043] (3) The stirred solution was poured into a high-pressure reactor, and 54 mL of 30% hydrogen peroxide was added (the molar ratio of FeSO4·7H2O to H2O2 was 1:3.26, and the mass ratio of H2O2 to COD was about 1:1). The autoclave was closed, and oxygen was introduced into it to make the pressure reach 0.4 MPa. The temperature of the first reaction (Fenton oxidation reaction) was set to 30°C, the speed was set to 600 rpm, and the reaction time was 2 h. The temperature of the second reaction (wet catalytic oxidation) was set to 140°C, the speed was set to 600 rpm, and the reaction time was 2 h.

[0044] (4) Pour the solution from (3) into a beaker and allow it to cool to room temperature. Place the beaker on a magnetic stirrer, add a magnetic stirrer, adjust the speed to 200 rpm, and stir continuously. Simultaneously, add sodium hydroxide to the solution and use a pH meter to monitor and control the pH of the solution in real time until the pH is adjusted to 8. Then, add 0.45 g of PAC to the beaker, followed by 4.5 mL of a 1200W molecular weight PAM solution (mass concentration 1‰), and finally filter the solution.

[0045] (5) Pour the filtrate into a beaker, place the beaker on a magnetic stirrer, add a stirring magnet, adjust the speed to 200 rpm, and stir continuously. Add sulfuric acid dropwise to the filtrate, and use a pH meter to monitor and control the pH value of the solution in real time while stirring continuously until the pH value of the solution is maintained in the range of 6 to 7. Then add the filtrate into the ozone catalytic oxidation reactor. The reactor is filled with an activated carbon-supported catalyst, and the filling height is 50% of the reactor height. The ozone generation capacity of the air source ozone generator is 10 g / h. The ozone flow rate in the reactor is controlled to be 30 L / h. After reacting for 0.5 h, filter the mixture, add 0.2 g of aluminum sulfate, stir for 10 min, filter the mixture, and the effluent phosphorus is 6.98 mg / L. The waste gas generated by the ozone catalytic oxidation process enters the ozone cracking device for treatment.

[0046] Example 2

[0047] A method for removing organic phosphorus from extraction wastewater in the hydrometallurgical industry comprises the following specific steps:

[0048] (1) Take 1.5 L of the raffinate after lithium extraction (oil content of 33.5 mg / L, COD of 800 mg / L, P of 36 mg / L) in a beaker, adjust the pH to 4, add 1.5 g of ferrous sulfate, place the beaker in an ultrasonic cleaning machine, set the temperature to 40 ° C, and react for 1 h to demulsify and remove oil.

[0049] (2) Remove the beaker and remove the floating oil and sediment on the water surface. Place the beaker on a magnetic stirrer, add a stirring magnet, adjust the speed to 200 rpm, and stir continuously. Detect the COD value at this time. Simultaneously, add sulfuric acid dropwise to the deoiled raffinate. Monitor the pH value of the solution in real time with a pH meter while stirring continuously until the pH of the solution is adjusted to 3. Then, add 2.25 g of ferrous sulfate heptahydrate.

[0050] (3) Pour the stirred solution into a high-pressure reactor, add 4.8 mL of 30% hydrogen peroxide (the molar ratio of FeSO4·7H2O to H2O2 is 1:5.81, and the mass ratio of H2O2 to COD is about 1.5:1), close the autoclave, and introduce oxygen into it to make the pressure reach 0.2 MPa. The first-stage reaction temperature is set to 30°C, the speed is set to 600 rpm, and the reaction time is 2 h. The second-stage reaction temperature is set to 130°C, the speed is set to 600 rpm, and the reaction time is 2 h.

[0051] (4) Pour the solution from step (3) into a beaker and allow it to cool to room temperature. Place the beaker on a magnetic stirrer, add a magnetic stirrer, adjust the speed to 200 rpm, and stir continuously. Simultaneously, add sodium hydroxide to the solution and use a pH meter to monitor and control the pH of the solution in real time until the pH is adjusted to 8. Then, add 0.45 g of PAC to the beaker, followed by 4.5 mL of a 1200 W molecular weight PAM solution (mass concentration 1‰), and finally filter the solution.

[0052] (5) Pour the filtrate into a beaker, place the beaker on a magnetic stirrer, add a stirring magnet, adjust the speed to 200 rpm, and stir continuously. Add sulfuric acid to the filtrate, and use a pH meter to monitor and control the pH value of the solution in real time while stirring continuously until the pH value of the solution is maintained in the range of 6 to 7. Then add it to the ozone catalytic oxidation reactor. The reactor is filled with activated carbon-supported catalyst, and the filling height is 50% of the reactor height. The ozone generation capacity of the air source ozone generator is 10 g / h. The ozone flow rate in the reactor is controlled to be 30 L / h. After reacting for 0.5 h, filter it, add 0.1 g of aluminum sulfate, stir for 10 min, and filter it. The phosphorus content of the effluent is 0.82 mg / L. The waste gas generated by the ozone catalytic oxidation process enters the ozone cracking device for treatment.

[0053] Example 3

[0054] A method for removing organic phosphorus from extraction wastewater in the hydrometallurgical industry comprises the following specific steps:

[0055] (1) Take 1.5 L of the raffinate after nickel and cobalt extraction (oil content is 47 mg / L, COD is 1900 mg / L, P is 82 mg / L) in a beaker, adjust the pH to 4, add 3 g of ferrous sulfate, place the beaker in an ultrasonic cleaning machine, set the temperature to 40 ° C, and react for 1 hour to demulsify and remove oil.

[0056] (2) Remove the beaker and remove the floating oil and sediment on the water surface. Place the beaker on a magnetic stirrer, add a stirring magnet, adjust the speed to 200 rpm, and stir continuously. Detect the COD value at this time. Simultaneously, add sulfuric acid dropwise to the deoiled raffinate. Monitor the pH value of the solution in real time with a pH meter while stirring continuously until the pH of the solution is adjusted to 3. Then, add 5.25 g of ferrous sulfate heptahydrate.

[0057] (3) Pour the stirred solution into a high-pressure reactor, add 7.6 mL of 30% hydrogen peroxide (the molar ratio of FeSO4·7H2O to H2O2 is 1:3.94, and the mass ratio of H2O2 to COD is about 1:1), close the autoclave, and introduce oxygen into it to make the pressure reach 0.2 MPa. The first-stage reaction temperature is set to 30°C, the speed is set to 600 rpm, and the reaction time is 2 h. The second-stage reaction temperature is set to 120°C, the speed is set to 600 rpm, and the reaction time is 2 h.

[0058] (4) Pour the solution from the reaction in (3) into a beaker and allow it to cool to room temperature. Place the beaker on a magnetic stirrer, add a magnetic stirrer, adjust the speed to 200 rpm, and stir continuously. At the same time, add sodium hydroxide to the solution and use a pH meter to monitor and control the pH value of the solution in real time. Adjust the pH to 7.5. Then add 0.45 g of PAC to the beaker, and then add 4.5 mL of a 1200W molecular weight PAM solution (mass concentration 1‰). Finally, filter the solution.

[0059] (5) Pour the filtrate into a beaker, place the beaker on a magnetic stirrer, add a stirring magnet, adjust the speed to 200 rpm, and stir continuously. Add sulfuric acid to the filtrate dropwise, and use a pH meter to monitor and control the pH value of the solution in real time under continuous stirring until the pH of the solution is maintained in the range of 6 to 7. Then add it to the ozone catalytic oxidation reactor. The reactor is filled with an activated carbon-supported catalyst, and the filling height is 50% of the reactor height. The ozone generation capacity of the air source ozone generator is 10 g / h. The ozone flow rate in the reactor is controlled to be 30 L / h. After reacting for 0.5 h, filter it, add 0.2 g of aluminum sulfate, stir for 10 min, and filter it. The phosphorus content of the effluent is 1.79 mg / L. The waste gas generated by the ozone catalytic oxidation process enters the ozone cracking device for treatment.

[0060] Comparative Example 1

[0061] 1.5L of the raffinate before lithium extraction (oil content of 34mg / L, COD of 1100mg / L, P of 39mg / L) was placed in a beaker. After direct ultrasonic deoiling without adding ferrous sulfate, the floating oil and sediment on the water surface were removed and the COD value at this time was detected. The solution was poured into a high-pressure reactor. Only one reaction was set in the reactor. 4.6g of ferrous sulfate heptahydrate and 5.5mL of 30% hydrogen peroxide were added (the molar ratio of FeSO4·7H2O to H2O2 was 1:3.26, and the mass ratio of H2O2 to COD was about 1.11:1). Oxygen was introduced to reach a pressure of 0.4MPa. The reaction temperature was set to 30℃, the speed was set to 600rpm, the reaction time was 2h, sodium hydroxide was added to the effluent, and a pH meter was used to monitor and control the pH value of the solution in real time and adjust the pH to 7.5. Then add 0.45g PAC to the beaker, and then add 4.5mL of 1200W molecular weight PAM solution (mass concentration 1‰), and then filter the solution. The oil content of the filtrate is 29.50mg / L. It is added to the silica-aluminum-based filler ozone catalytic reactor for reaction, and the ozone flow rate is controlled to be 30L / h for 0.5h. After filtration, 0.1g of aluminum sulfate is added to the filtrate, stirred for 10min, and then filtered. The filtrate P is 22.12mg / L. The silica-aluminum-based filler is an ozone catalyst for conventional sewage terminal treatment, mainly composed of aluminum oxide, silicon dioxide, and magnesium chromium zirconium oxide. The model used is RHCY02, which is filled to 50% of the height of the ozone catalytic oxidation reactor.

[0062] Test example

[0063] The phosphorus content of the solutions in each treatment stage of Examples 1, 2, 3 and Comparative Example 1 was detected, and the results are shown in Table 1.

[0064] Table 1 Phosphorus removal data

[0065] Among them, total removal rate % = (phosphorus content in the original solution - phosphorus content in the effluent after ozone catalytic oxidation) / phosphorus content in the original solution * 100%.

[0066] The removal effect of ultrasonic degreasing with ferrous sulfate is most obvious when the P concentration is high (Example 1), and the removal effects of other examples are also better than those of the comparative examples. Taking Example 2 as an example, the P removal rate of ultrasonic degreasing with ferrous sulfate is (36.46-30.24) / 36.46≈17.06%, while the P removal rate of direct ultrasonic degreasing without ferrous sulfate is (39.34-36.88) / 39.34≈6.25%; the P removal rate of the two-stage reaction process in the reactor of Example 2 is (30.24-9.07) / 30.24≈70%, while the P removal rate of the comparative example 1 is (30.24-9.07) / 30.24≈70%, and the P removal rate of the direct ultrasonic degreasing without catalytic oxidation of organic phosphorus oxide is (30.24-9.07) / 30.24≈70%. The removal rate of inorganic phosphorus during the conversion process was only (39.34-29.50) / 39.34≈20.01%. In Example 2, the ozone-catalyzed oxidation (activated carbon-supported catalyst) and the phosphorus removal process with the addition of aluminum sulfate achieved a P removal rate of (9.07-0.82) / 9.07≈90.96%. In Comparative Example 1, the ozone-catalyzed oxidation with a silica-alumina-based filler catalyst and the phosphorus removal process with the addition of aluminum sulfate achieved a P removal rate of (29.50-22.12) / 29.50≈25.02%. The overall organic phosphorus removal rate of Example 2 reached 97.76%, significantly higher than the 43.77% removal rate of Comparative Example 1.

Claims

1. A method for removing phosphorus from extraction wastewater in the hydrometallurgical industry, characterized in that: The following steps are involved: S1: adjusting the pH of the extracted wastewater to 3.5-4.5, adding ferrous sulfate and then performing ultrasonic treatment to obtain a suspension; S2: separating the suspension into solid and liquid, taking the liquid phase for stirring, adding acid to adjust the pH to 3-3.5, adding ferrous sulfate and hydrogen peroxide, introducing oxygen to increase pressure, and heating for reaction; S3: After adding alkali solution to adjust the pH to 7.5-8, add coagulant and flocculant in sequence, separate the solid and liquid, adjust the pH to 6-7, perform ozone oxidation, add aluminum sulfate after the reaction is completed, and detect the water phosphorus content after solid-liquid separation.

2. The method for removing phosphorus from extraction wastewater in hydrometallurgical industry according to claim 1, characterized in that: In step S1, the solid-to-liquid ratio of the ferrous sulfate to the extraction wastewater is 0.001 to 0.01 g / mL.

3. The method for removing phosphorus from extraction wastewater in hydrometallurgical industry according to claim 1, characterized in that: In step S1, the ultrasonic treatment is performed at 30-40°C; the frequency of the ultrasonic treatment is 35-40KHz; and the time of the ultrasonic treatment is 0.5-1h.

4. The method for removing phosphorus from extraction wastewater in hydrometallurgical industry according to claim 1, characterized in that: In step S2, the molar ratio of ferrous sulfate to hydrogen peroxide is 1:(3-10).

5. The method for removing phosphorus from extraction wastewater in hydrometallurgical industry according to claim 1 or 4, characterized in that: In step S2, the concentration of the hydrogen peroxide is 27.5% to 35%; and / or the mass ratio of the hydrogen peroxide to the COD of the extraction wastewater is (1 to 2):

1.

6. The method for removing phosphorus from extraction wastewater in hydrometallurgical industry according to claim 1, characterized in that: In step S2, the oxygen is introduced to pressurize the mixture so that the pressure reaches 0.2-0.5 MPa.

7. The method for removing phosphorus from extraction wastewater in hydrometallurgical industry according to claim 1, characterized in that: In step S2, the temperature-raising reaction is a two-stage reaction; wherein the temperature of the first stage reaction is 30-40°C, and the reaction time is 2-3h; the temperature of the second stage reaction is 120-150°C, and the reaction time is 1-2h.

8. The method for removing phosphorus from extraction wastewater in hydrometallurgical industry according to claim 1, characterized in that: In step S3, the coagulant is polyaluminium chloride; polyaluminium chloride is added so that the concentration of the polyaluminium chloride is 200-300 ppm.

9. The method for removing phosphorus from extraction wastewater in hydrometallurgical industry according to claim 8, characterized in that: The basicity of the polyaluminium chloride is 60% to 80%.

10. The method for removing phosphorus from extraction wastewater in hydrometallurgical industry according to claim 1, characterized in that: In step S3, the flocculant is polyacrylamide; and / or the molecular weight of the polyacrylamide is about 1200W; and / or the amount of polyacrylamide added is 3-5 ppm.

11. The method for removing phosphorus from extraction wastewater in hydrometallurgical industry according to claim 1, characterized in that: In step S3, the ozone oxidation uses activated carbon loaded with metal oxides as a catalyst.

12. The method for removing phosphorus from extraction wastewater in hydrometallurgical industry according to claim 11, characterized in that: The metal oxide is at least one of titanium dioxide, copper oxide or manganese dioxide.

13. The method for removing phosphorus from extraction wastewater in hydrometallurgical industry according to claim 1, characterized in that: In step S3, the ozone oxidation time is 10 to 30 minutes.

14. The method for removing phosphorus from extraction wastewater in hydrometallurgical industry according to claim 1, characterized in that: In step S3, the amount of aluminum sulfate added is 50 to 200 ppm.

15. A method for recycling lithium batteries, comprising the steps of the method for removing phosphorus from extraction wastewater in the hydrometallurgical industry as described in any one of claims 1 to 14.

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