A method for recovering nickel and phosphorus from a waste solution of electroless nickel plating

Abstract

The application discloses a method for recovering nickel and phosphorus from electroless nickel plating waste liquid, and the method comprises the following steps: preparing nickel sulfate through extraction and stripping, and preparing iron phosphate through Fenton oxidation and precipitation; compared with the prior art, the method is characterized in that the waste liquid is pretreated, insoluble solid particles in the waste liquid are removed, emulsification of an extractant caused by particles in a subsequent extraction process is prevented, damage to extraction oil is avoided, and the extraction efficiency is ensured; in addition, the extractant used in the method can be recycled, secondary pollution is avoided, and the method is economical and practical; in the method, main pollutants in waste water are all converted into important chemical raw materials, recycling is realized, sulfuric acid and Fenton reagents used are all converted into terminal products, difficulty of end waste water treatment is not increased, clean production is met, the treatment cost is low, the product has high added value, and the method has strong practicability.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of resource utilization of electroless nickel plating waste liquid, in particular to a method for recovering nickel and phosphorus from electroless nickel plating waste liquid. BACKGROUND

[0002] Surface treatment is an important technology that has emerged with the development of industry. By changing the mechanical, physical and chemical properties of the substrate through surface treatment, important functions such as corrosion resistance, wear resistance, electrical conductivity, high-temperature oxidation resistance and decoration can be achieved. Surface treatment plays an important role in the field of steel corrosion protection, greatly extending the service life of metals and having important significance. Chemical plating is an important technology in the surface treatment industry. Unlike electroplating technology, chemical plating can not only plate a layer of metal surface on the surface of conductive materials, but also form a layer of plating on the surface of non-conductive materials. This technology is based on redox reaction and uses strong reducing agents to deposit metal ions in the solution to obtain a dense plating layer. It can be uniformly plated on the surface of complex-shaped substrates. Due to its simple process, it is widely used, and currently chemical zinc plating and chemical nickel plating are the most widely used. The nickel used in chemical nickel plating is a heavy metal that can cause cancer, teratogenicity and mutagenicity. At the same time, the solution also contains various environmental pollution factors, including a large amount of phosphorus elements and organic matter, which can cause serious water pollution (including eutrophication) and need to be scientifically treated and disposed.

[0003] Shi Yini (Industrial Research on Treatment of Electroless Nickel Plating Waste Liquid) proposed using sodium borohydride exchange method to recover metal nickel in waste liquid, and the removal recovery rate reached 94.2%. This method uses the principle of electroless nickel plating and uses more reducing agents to treat nickel in waste liquid. The method is simple, but the treatment cost is high and the recovery rate is low. Patent CN202210535061 proposes a method for recovering nickel, which uses electrochemical deposition technology to recover metal nickel on a foamed nickel cathode, and obtains foamed nickel with catalytic performance, which can be used as an electrode for catalytic hydrogen production. This patent uses electrolysis to recover foamed nickel, which is simple to operate and relatively clean and environmentally friendly, and has certain reference value. Patent CN202110836834 proposes a method for recovering nickel and phosphorus from electroless nickel plating waste liquid, which uses electrodialysis method to obtain phosphorus concentrate and nickel concentrate respectively; the phosphorus concentrate is converted into iron phosphate by electro-Fenton method for recovery; the nickel concentrate is recovered by electrodeposition method. The method used is also simple to operate and relatively clean and environmentally friendly, but the investment is large and has certain reference value. Patent CN202011600969 proposes a complete treatment process, which first pretreats the nickel plating waste liquid by using supported heterogeneous Fenton catalytic oxidation technology, controls the reaction conditions, recovers nickel phosphate product by adding excess nickel salt, adjusts the pH to recover nickel hydroxide product, and finally prepares acid and sodium hydroxide solution by double-membrane electrodialysis method to realize waste liquid system treatment, which is clean and environmentally friendly, but the investment is large and has certain reference value.

[0004] The electroless nickel plating waste liquid contains nickel and a large amount of phosphorus elements. In the current stage of rapid development of battery energy storage technology, it has important economic value to recover nickel in the waste liquid as a raw material for synthesizing nickel-containing batteries and to recover phosphorus in the waste liquid as a raw material for synthesizing lithium iron phosphate batteries. However, the above methods need to add a large amount of sewage treatment agents, which is high in cost, and the recovery of heavy metals and phosphorus resources in the waste liquid is difficult, causing resource waste, generating a large amount of sludge and easily causing secondary pollution. SUMMARY

[0005] The purpose of the present application is to provide a new way to recover nickel and phosphorus from electroless nickel plating waste liquid and synthesize nickel sulfate and iron phosphate respectively, so as to realize resource recycling. In order to achieve the above purpose, the technical scheme adopted by the present application is: a method for recovering nickel and phosphorus from electroless nickel plating waste liquid, preparing nickel sulfate by extraction and stripping, and preparing iron phosphate by Fenton oxidation and precipitation, the method is realized by the following steps:

[0006] Waste liquid pretreatment: filtering the nickel plating waste liquid to remove insoluble solid particles in the waste liquid;

[0007] Waste liquid nickel recovery: adjusting the pH value of the filtered waste liquid to 5-6, mixing with the extractant, transferring the nickel in the waste liquid to the extractant by multi-stage extraction, mixing the oil phase after extraction with sulfuric acid to obtain a nickel sulfate solution, and obtaining nickel sulfate solid by concentrating and recrystallizing the nickel sulfate, and adding a heavy metal capturing agent and a high molecular precipitating agent to the waste liquid after extraction to completely remove nickel ions;

[0008] Waste liquid phosphorus recovery: adjusting the pH value of the waste liquid after removing nickel ions to 3-4 with 70vt% sulfuric acid, adding ferrous sulfate and hydrogen peroxide, oxidizing phosphorus to phosphate by the strong oxidizing groups generated by Fenton oxidation reaction, adding iron powder to remove magnetism and filtering, then adding hydrogen peroxide, stirring at 35-45℃ to oxidize all ferrous ions in the waste liquid to iron ions, adding iron sulfate solid, stirring to dissolve, and filtering after the molar ratio of phosphorus to iron in the waste liquid is 1:1, adjusting the pH value of the solution to 1-2 with 70vt% sulfuric acid, heating and aging, separating by pressure filtration and drying to obtain iron phosphate.

[0009] Further, in the waste liquid pretreatment process, a precision filter bag is used to filter the waste liquid to remove insoluble solid particles in the waste liquid and prevent the emulsification of the extractant caused by particles in the subsequent extraction process.

[0010] Further, in the waste liquid nickel recovery process, the pH value of the filtered waste liquid is adjusted to 5-6 with 70vt% sulfuric acid and nickel hydroxide.

[0011] Further, in the process of recovering nickel from waste liquid, the waste liquid is mixed with extractant in a volume ratio of (1:2) to (1:1), the extractant is prepared by mixing extract oil and diluent in a volume ratio of (1:4) to (1:1), the extract oil is diisooctyl phosphate P204 and / or 2-ethylhexyl phosphate 2-ethylhexyl ester P507, and the diluent is sulfonated kerosene.

[0012] Further, in the process of recovering nickel from waste liquid, the waste liquid is extracted with extractant in a multi-stage countercurrent manner, when the extract oil is diisooctyl phosphate P204, the number of multi-stage countercurrent extraction is (3-4), and when the extract oil is 2-ethylhexyl phosphate 2-ethylhexyl ester P507, the number of multi-stage countercurrent extraction is (3-4).

[0013] Further, in the process of recovering nickel from waste liquid, the waste liquid is extracted with extractant in a multi-stage countercurrent manner, when the extract oil is diisooctyl phosphate P204 and 2-ethylhexyl phosphate 2-ethylhexyl ester P507, the number of multi-stage countercurrent extraction is (2-4).

[0014] Further, in the process of recovering nickel from waste liquid, the oil phase after extraction is mixed with sulfuric acid in a volume ratio of (2:1) to (1:1), and nickel sulfate solution is obtained by back extraction, and the concentration of the sulfuric acid is 20-40vt%.

[0015] Further, in the process of recovering nickel from waste liquid, the heavy metal capture agent used is HMC-M2, and the high molecular precipitant used is polyacrylamide PAM.

[0016] Further, in the process of recovering phosphorus from waste liquid, after the pH value of the waste liquid from which nickel ions have been removed is adjusted to 3-4 with 70vt% sulfuric acid, 30-50wt% ferrous sulfate is added, then 20-30wt% hydrogen peroxide is added, and the mixture is stirred and reacted at 35-45℃ for 1-3h, the mass concentration ratio of the ferrous sulfate to the hydrogen peroxide is (4:1) to (3:1), and the amount of hydrogen peroxide added is determined according to the total amount of chemical oxygen demand COD in the waste liquid, and the mass concentration ratio of COD to hydrogen peroxide is (1:1) to (1:2).

[0017] Further, in the process of recovering phosphorus from waste liquid, after Fenton oxidation reaction, iron powder is added for demagnetization and filtration, then 20-40vt% hydrogen peroxide is added, the mixture is stirred until all the ferrous ions in the solution are oxidized to ferric ions, then solid ferric sulfate is added and stirred until the molar ratio of phosphorus to iron in the solution is 1:1, the mixture is stirred at 35-45℃, the pH value of the solution is adjusted to 1-2 with 70vt% sulfuric acid, the mixture is heated to 70℃, and then aged, filtered, washed, and dried to obtain ferric phosphate solid.

[0018] The beneficial effects of the present application are that, compared with the prior art, the present application pretreats waste liquid, removes insoluble solid particles in the waste liquid to prevent emulsification of the extractant caused by particles in the subsequent extraction process, avoids damage to the extraction oil, ensures the extraction efficiency, and the extractant used in the present application can be recycled, avoiding secondary pollution and being economical and practical; the method of the present application converts the main pollutants in waste water into important chemical raw materials, realizes recycling, converts sulfuric acid and Fenton reagent used into end products, does not increase the difficulty of end waste water treatment, meets clean production, has low treatment cost, high product added value, and strong practicability. BRIEF DESCRIPTION OF DRAWINGS

[0019] The drawings described herein are used to provide further understanding of the present application, constitute a part of the present application, the illustrative embodiments of the present application and the description thereof are used to explain the present application, and do not constitute improper limitation on the present application. In the drawings:

[0020] Figure 1 is a process flow diagram of the present application;

[0021] Figure 2 is a process flow diagram of the present application. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be clearly and completely described below, obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0023] Embodiment 1

[0024] A method for recovering nickel and phosphorus from electroless nickel plating waste liquid, preparing nickel sulfate by extraction and stripping, and preparing iron phosphate by Fenton oxidation and precipitation.

[0025] In this embodiment, the nickel ion content is 3300 mg / L, the total phosphorus content is 9300 mg / L, the COD content is 83300 mg / L, and the initial pH value is 4.58.

[0026] Waste liquid pretreatment: the nickel plating waste liquid is filtered by a precision filter bag to remove black insoluble solid particles in the waste liquid. Then the filtered waste liquid is detected, and it is found that the nickel ion content in the waste liquid is 3300 mg / L, the total phosphorus content is 9300 mg / L, the COD content is 82900 mg / L, and the pH value is 4.58, indicating that the insoluble solid particles in the waste liquid are organic matter, and removing the insoluble solid particles in the solution can prevent emulsification of the extractant caused by insoluble substances in the subsequent extraction process, and damage the extraction function of the extractant.

[0027] Spent liquor nickel recovery: The pH of the filtered spent liquor is adjusted to 6 with 70% sulfuric acid and nickel hydroxide. 1000 mL of the spent liquor is mixed with the extractant, and the spent liquor and extractant are mixed in a volume ratio of 1:1 and stirred. The extraction is carried out by 3-stage countercurrent extraction. The extractant is prepared by mixing extract oil and diluent in a volume ratio of 1:4, the extract oil is diisooctyl phosphite P204, and the diluent is sulfonated kerosene. The oil phase after extraction is mixed with 20% sulfuric acid in a volume ratio of 2:1 to obtain a nickel sulfate solution. The nickel ion content in the solution after extraction is 48.3 mg / L, and the removal rate of nickel reaches 98.54%. The spent liquor after extraction is filtered by adding heavy metal capture agent HMC-M2 and high molecular precipitant polyacrylamide PAM to completely remove the nickel ions.

[0028] Spent liquor phosphorus recovery: After adjusting the pH of the spent liquor from which the nickel ions have been removed to 4 with 70% sulfuric acid, 155 grams of 30% ferrous sulfate solution (in a ratio of ferrous sulfate: hydrogen peroxide = 3:1) and 553 grams of 30% hydrogen peroxide solution (in a ratio of COD: hydrogen peroxide = 1:2) are added according to the total amount of COD in the spent liquor, and the mixture is stirred and reacted at 35°C for 3 hours. The strong oxidizing groups generated by the Fenton oxidation reaction oxidize the phosphorus to phosphate. After demagnetization and filtration by adding 5 grams of iron powder, 130 grams of 30% hydrogen peroxide solution is added, the mixture is stirred and reacted for 0.5 hours to oxidize all the ferrous ions to iron ions in the solution, and then 1080 grams of solid iron sulfate is added to precipitate all the phosphate. The solution is filtered, the pH of the solution is adjusted to 2 with 70% sulfuric acid, and the solution is heated to 70°C. After aging, pressure filtration, washing, and drying, iron phosphate solid is obtained.

[0029] Example 2

[0030] A method for recovering nickel and phosphorus from electroless nickel plating spent liquor, which prepares nickel sulfate by extraction and back extraction, and then prepares iron phosphate by Fenton oxidation and precipitation.

[0031] In this example, the nickel ion content is 3300 mg / L, the total phosphorus content is 9300 mg / L, the COD content is 83300 mg / L, and the initial pH is 4.58.

[0032] Spent liquor pretreatment: The spent nickel plating liquor is filtered using a precision filter bag to remove black insoluble solid particles in the spent liquor. Then the filtered spent liquor is detected, and it is found that the nickel ion content in the spent liquor is 3300 mg / L, the total phosphorus content is 9300 mg / L, the COD content is 82900 mg / L, and the pH is 4.58, indicating that the insoluble solid particles in the spent liquor are organic matter. Removing insoluble solid particles from the solution can prevent emulsification of the extractant caused by insoluble substances in the subsequent extraction process, and damage the extraction function of the extractant.

[0033] Nickel recovery from waste liquid: The pH of the filtered waste liquid was adjusted to 5 using 70 vt% sulfuric acid and nickel hydroxide. 1000 mL of the waste liquid was mixed with an extractant at a volume ratio of 1:2, and the mixture was stirred and extracted using a three-stage countercurrent process. The extractant was prepared by mixing an extractant oil and a diluent at a volume ratio of 1:1. The extractant oil was 2-ethylhexyl phosphate (P507), and the diluent was sulfonated kerosene. The extracted oil phase was back-extracted with 40 vt% sulfuric acid at a volume ratio of 1:1 to obtain a nickel sulfate solution. After extraction, the nickel ion content in the solution was measured to be 28.5 mg / L, with a nickel removal rate of 99.07%. The extracted waste liquid was then filtered with a heavy metal scavenger HMC-M2 and a high molecular weight precipitant polyacrylamide (PAM) to completely remove nickel ions.

[0034] Phosphorus recovery from waste liquid: After adjusting the pH of the nickel-removed waste liquid to 3 with 70 vt% sulfuric acid, 95 g of 50% ferrous sulfate solution (hydrogen peroxide:ferrous sulfate = 4:1 ratio) was added according to the total COD in the waste liquid. Then, 593 g of 20% hydrogen peroxide solution (COD:hydrogen peroxide = 1:1 ratio) was added, and the mixture was stirred at 45°C for 1 hour. The strong oxidizing groups generated by the Fenton oxidation reaction oxidized phosphorus to phosphate. After adding 5 g of iron powder for demagnetization and filtering, 100 g of 40% hydrogen peroxide solution was added, and the mixture was stirred for 0.5 hours to oxidize all the ferrous ions in the solution to ferric ions. Then, 1212 g of ferric sulfate solid was added to precipitate all the phosphate ions. After filtering, the pH of the solution was adjusted to 1 with 70 vt% sulfuric acid, heated to 70°C, aged, filtered under pressure, washed, and dried to obtain solid ferric phosphate.

[0035] Example 3

[0036] A method for recovering nickel and phosphorus from chemical nickel plating waste liquid involves preparing nickel sulfate through extraction and back-extraction, followed by preparing iron phosphate through Fenton oxidation and precipitation.

[0037] In this embodiment, the nickel ion content is 3300 mg / L, the total phosphorus content is 9300 mg / L, the COD content is 83300 mg / L, and the initial pH value is 4.58.

[0038] Waste liquid pretreatment: The nickel plating waste liquid was filtered using a precision filter bag to remove black insoluble solid particles. The filtered waste liquid was then tested and found to contain 3300 mg / L nickel ions, 9300 mg / L total phosphorus, 82900 mg / L COD, and a pH of 4.58. This indicates that the insoluble solid particles in the waste liquid were organic matter. Removing these particles prevents the extractant from emulsifying during subsequent extraction processes, thus preserving its extraction function.

[0039] Waste liquid nickel recovery: the pH value of the filtered waste liquid is adjusted to 5 with 70% sulfuric acid and nickel hydroxide. 1000 mL of waste liquid is mixed with extractant. The waste liquid and extractant are mixed and stirred at a volume ratio of 1:1.5. The first stage uses diisooctyl phosphoric acid (P204) extractant oil, and the second stage uses 2-ethylhexyl phosphoric acid 2-ethylhexyl ester (P507) extractant oil. The extractant is prepared by mixing extractant oil and diluent sulfonated kerosene at a volume ratio of 1:3. Extraction is carried out by countercurrent method in two stages. The extracted oil phase is mixed with 40% sulfuric acid at a volume ratio of 1.5:1 to obtain a nickel sulfate solution. The nickel ion content in the solution after extraction is 20.9 mg / L, and the removal rate of nickel reaches 99.22%. After extraction, the waste liquid is filtered with heavy metal capture agent HMC-M2 and high molecular precipitant polyacrylamide PAM to completely remove nickel ions.

[0040] Waste liquid phosphorus recovery: after adjusting the pH value of the waste liquid from which the nickel ions have been removed to 3 with 70% sulfuric acid, 100 grams of 40% ferrous sulfate solution (according to the ratio of hydrogen peroxide: ferrous sulfate = 3.5:1) are added according to the total COD in the waste liquid, followed by 565 grams of 25% hydrogen peroxide solution (according to the ratio of COD: hydrogen peroxide = 1:1.5). Stirring and reaction at 40°C for 2 hours. The strong oxidizing groups generated by Fenton oxidation reaction oxidize phosphorus to phosphate. After demagnetization and filtration by adding 5 grams of iron powder, 150 grams of 20% hydrogen peroxide solution are added, and the solution is stirred and reacted for 0.5 hours to oxidize all the ferrous ions to iron ions. Then, 1160 grams of solid iron sulfate are added to precipitate all the phosphate. After filtration, the pH value of the solution is adjusted to 1 with 70% sulfuric acid, heated to 70°C, and then aged, filtered, washed, and dried to obtain iron phosphate solid.

[0041] Example 4

[0042] A method for recovering nickel and phosphorus from electroless nickel plating waste liquid, which prepares nickel sulfate by extraction and stripping, and then prepares iron phosphate by Fenton oxidation and precipitation.

[0043] In this example, the nickel ion content is 3300 mg / L, the total phosphorus content is 9300 mg / L, the COD content is 83300 mg / L, and the initial pH value is 4.58.

[0044] Waste liquid pretreatment: The nickel plating waste liquid is filtered with a precision filter bag to remove black insoluble solid particles in the waste liquid. Then the filtered waste liquid is detected, and it is found that the nickel ion content in the waste liquid is 3300 mg / L, the total phosphorus content is 9300 mg / L, the COD content is 82900 mg / L, and the pH value is 4.58. This indicates that the insoluble solid particles in the waste liquid are organic matter. Removing insoluble solid particles from the solution can prevent emulsification of the extractant caused by insoluble substances in the subsequent extraction process, which can damage the extraction function of the extractant.

[0045] Waste liquid nickel recovery: the pH value of the filtered waste liquid is adjusted to 6 with 70% sulfuric acid and nickel hydroxide, 1000 mL of waste liquid is mixed with extractant, the waste liquid and extractant are mixed and stirred according to a volume ratio of 1:2, and extraction is carried out by 4-stage countercurrent. The extractant is prepared by mixing extract oil and diluent according to a volume ratio of 1:3, the extract oil is diisooctyl phosphate P204, and the diluent is sulfonated kerosene. The oil phase after extraction is mixed with 30% sulfuric acid according to a volume ratio of 1.5:1, and nickel sulfate solution is obtained by back extraction. The nickel ion content in the solution after extraction is 26.1 mg / L, and the removal rate of nickel reaches 99.14%. The waste liquid after extraction is filtered by adding heavy metal capture agent HMC-M2 and high molecular precipitant polyacrylamide PAM, and the nickel ions are completely removed.

[0046] Waste liquid phosphorus recovery: after the pH value of the waste liquid from which the nickel ions have been removed is adjusted to 3 with 70% sulfuric acid, 155 grams of ferrous sulfate solution with a mass concentration of 40% (according to a ratio of ferrous sulfate: hydrogen peroxide = 3:1) and 524 grams of hydrogen peroxide solution with a mass concentration of 25% (according to a ratio of COD: hydrogen peroxide = 1:2) are added according to the total amount of COD in the waste liquid, and the mixture is stirred and reacted at 40°C for 2 hours. The strong oxidizing groups generated by the Fenton oxidation reaction oxidize phosphorus to phosphate, 5 grams of iron powder is added to remove magnetism and filter, then 142 grams of 20% hydrogen peroxide solution is added, the mixture is stirred and reacted for 0.5 hours to oxidize all the ferrous ions to iron ions, and then 1117 grams of solid iron sulfate is added to precipitate all the phosphate, the mixture is filtered, the pH value of the solution is adjusted to 2 with 30% sulfuric acid, the solution is heated to 70°C, and then aged, pressure filtered, washed, and dried to obtain iron phosphate solid.

[0047] Example 5

[0048] A method for recovering nickel and phosphorus from electroless nickel plating waste liquid, which comprises preparing nickel sulfate by extraction and back extraction, and preparing iron phosphate by Fenton oxidation and precipitation.

[0049] In this example, the nickel ion content is 3300 mg / L, the total phosphorus content is 9300 mg / L, the COD content is 83300 mg / L, and the initial pH value is 4.58.

[0050] Waste liquid pretreatment: The nickel plating waste liquid is filtered by using a precision filter bag to remove black insoluble solid particles in the waste liquid. Then the filtered waste liquid is detected, and it is found that the nickel ion content in the waste liquid is 3300 mg / L, the total phosphorus content is 9300 mg / L, the COD content is 82900 mg / L, and the pH value is 4.58, indicating that the insoluble solid particles in the waste liquid are organic matter. Removing insoluble solid particles from the solution can prevent emulsification of the extractant caused by insoluble substances in the subsequent extraction process, and damage the extraction function of the extractant.

[0051] Waste liquid nickel recovery: the pH value of the filtered waste liquid is adjusted to 5 with 70% sulfuric acid and nickel hydroxide. 1000 mL of waste liquid is mixed with extractant, and the waste liquid and extractant are mixed and stirred at a volume ratio of 1:1.5. Extraction is carried out by 4-stage countercurrent. The extractant is prepared by mixing extractant oil and diluent at a volume ratio of 1:2, the extractant oil is 2-ethylhexyl phosphonic acid 2-ethylhexyl ester P507, and the diluent is sulfonated kerosene. The oil phase after extraction is mixed with 30% sulfuric acid at a volume ratio of 1.5:1, and nickel sulfate solution is obtained by back extraction. The nickel ion content in the solution after extraction is 25.8 mg / L, and the removal rate of nickel reaches 99.36%. After extraction, the waste liquid is filtered by adding heavy metal capture agent HMC-M2 and high molecular precipitant polyacrylamide PAM to completely remove nickel ions.

[0052] Waste liquid phosphorus recovery: after adjusting the pH value of the waste liquid from which the nickel ions have been removed to 3 with 70% sulfuric acid, 115 grams of 40% ferrous sulfate solution (according to the ratio of hydrogen peroxide: ferrous sulfate = 4:1) are added according to the total COD in the waste liquid, followed by 602 grams of 30% hydrogen peroxide solution (according to the ratio of COD: hydrogen peroxide = 1:2). Stirring and reaction at 45°C for 1h. The strong oxidizing groups generated by the Fenton oxidation reaction oxidize the phosphorus to phosphate. After demagnetization and filtration by adding 5 grams of iron powder, 120 grams of 30% hydrogen peroxide solution are added, and the solution is stirred and reacted for 0.5h to oxidize all the ferrous ions to iron ions. Then, 1145 grams of iron sulfate solid are added to precipitate all the phosphate. After filtration, the pH value of the solution is adjusted to 1 with 70% sulfuric acid, heated to 70°C, and then aged, filtered, washed, and dried to obtain iron phosphate solid.

[0053] Example 6

[0054] A method for recovering nickel and phosphorus from electroless nickel plating waste liquid, which prepares nickel sulfate by extraction and back extraction, and then prepares iron phosphate by Fenton oxidation and precipitation.

[0055] In this example, the nickel ion content is 3300 mg / L, the total phosphorus content is 9300 mg / L, the COD content is 83300 mg / L, and the initial pH value is 4.58.

[0056] Waste liquid pretreatment: The nickel plating waste liquid is filtered by using a precision filter bag to remove black insoluble solid particles in the waste liquid. Then the filtered waste liquid is detected, and it is found that the nickel ion content in the waste liquid is 3300 mg / L, the total phosphorus content is 9300 mg / L, the COD content is 82900 mg / L, and the pH value is 4.58. This indicates that the insoluble solid particles in the waste liquid are organic matter, and removing insoluble solid particles from the solution can prevent emulsification of the extractant caused by insoluble substances in the subsequent extraction process, which can damage the extraction function of the extractant.

[0057] Waste liquid nickel recovery: the pH value of the filtered waste liquid is adjusted to 5 by 70% sulfuric acid and nickel hydroxide, 1000 mL of waste liquid is mixed with extractant, the waste liquid and the extractant are mixed and stirred according to a volume ratio of 1:2, diisooctyl phosphate P204 extractive oil is used in the first and second stages, 2-ethylhexyl phosphate 2-ethylhexyl ester P507 extractive oil is used in the third and fourth stages, the extractant is obtained by mixing the extractive oil and the diluent sulfonated kerosene according to a volume ratio of 1:4, extraction is carried out by the fourth stage countercurrent method, the oil phase after extraction is mixed with 40% sulfuric acid according to a volume ratio of 1:1 to obtain a nickel sulfate solution, the nickel ion content in the solution after extraction is 19.8 mg / L, the removal rate of nickel reaches 99.37%, and the waste liquid after extraction is filtered by adding a heavy metal capturing agent HMC-M2 and a high molecular precipitant polyacrylamide PAM to completely remove the nickel ions.

[0058] Waste liquid phosphorus recovery: after the pH value of the waste liquid from which the nickel ions are removed is adjusted to 3 by 70% sulfuric acid, 120 grams of ferrous sulfate solution with a mass concentration of 30% (according to a ratio of hydrogen peroxide: ferrous sulfate = 3:1) and 555 grams of hydrogen peroxide solution with a mass concentration of 30% (according to a ratio of COD: hydrogen peroxide = 1:1) are added according to the total COD in the waste liquid, and the mixture is stirred and reacted at 35°C for 3h. The strong oxidizing groups generated by the Fenton oxidation reaction oxidize phosphorus to phosphate, 5 grams of iron powder is added to remove magnetism and filter, then 158 grams of 20% hydrogen peroxide solution is added, the mixture is stirred and reacted for 0.5h to oxidize all the ferrous ions in the solution to iron ions, then 1160 grams of solid iron sulfate is added to precipitate all the phosphate, the mixture is filtered, the pH value of the solution is adjusted to 1 by 70% sulfuric acid, the solution is heated to 70°C, and then aging, pressure filtration, washing and drying are carried out to obtain iron phosphate solid.

[0059] The above is only an embodiment of the present application and is not intended to limit the present application. The present application can have various modifications and changes for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the scope of the claims of the present application.

Claims

1. A method for recovering nickel and phosphorus from a waste solution of electroless nickel plating, preparing nickel sulfate by extraction and stripping, and preparing ferric phosphate by Fenton oxidation and precipitation, characterized by, The method is realized by the following steps: Waste liquid pretreatment: the waste liquid is filtered by a precision filter bag to remove insoluble solid particles in the waste liquid and prevent the emulsification of the extractant caused by particles in the subsequent extraction process; Waste liquid nickel recovery: the pH value of the filtered waste liquid is adjusted to 5-6 by 70wt% sulfuric acid and nickel hydroxide, the waste liquid is mixed with an extractant in a volume ratio of (1:2) to (1:1), the extractant is prepared by mixing extractant oil 2-ethylhexyl phosphonic acid 2-ethylhexyl ester P507 and diluent sulfonated kerosene in a volume ratio of (1:4) to (1:1), the nickel in the waste liquid is transferred to the extractant by multi-stage extraction, the oil phase after extraction is mixed with 20-40wt% sulfuric acid in a volume ratio of (2:1) to (1:1) to obtain a nickel sulfate solution by stripping, the nickel sulfate is concentrated and recrystallized to obtain nickel sulfate solid, and the waste liquid after extraction is filtered by adding heavy metal capture agent HMC-M2 and high molecular precipitant polyacrylamide PAM to completely remove nickel ions; Waste liquid phosphorus recovery: after adjusting the pH value of the waste liquid from which the nickel ions have been removed to 3-4 by 70wt% sulfuric acid, 30-50wt% ferrous sulfate is first added, then 20-30wt% hydrogen peroxide is added, and the mixture is stirred and reacted at 35-45℃ for 1-3h, the mass concentration ratio of the ferrous sulfate to the hydrogen peroxide is (4:1) to (3:1), the amount of hydrogen peroxide added is determined according to the total amount of chemical oxygen demand COD in the waste liquid, and the mass concentration ratio of COD to hydrogen peroxide is (1:1) to (1:2), strong oxidizing groups generated by Fenton oxidation reaction oxidize phosphorus to phosphate, after magnetic filtration by adding iron powder, 20-40wt% hydrogen peroxide is added, the mixture is stirred at 35-45℃ to oxidize all the ferrous ions in the waste liquid to ferric ions, then iron sulfate solid is added, the mixture is stirred and dissolved to make the molar ratio of phosphorus to iron in the waste liquid 1:1, then the mixture is filtered, the pH value of the solution is adjusted to 1-2 by 70wt% sulfuric acid, the solution is heated to 70℃ and aged, and then pressure filtration, washing and drying are performed to obtain iron phosphate.

2. The method for recovering nickel and phosphorus from electroless nickel plating waste solution according to claim 1, characterized in that, In the waste liquid nickel recovery process, the waste liquid and the extractant are extracted in a multi-stage countercurrent manner, and the number of multi-stage countercurrent extraction stages n is (3-4).

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