A method for treating nickel-containing wastewater and recycling the same

Abstract

The present invention belongs to the technical field of wastewater treatment, and specifically relates to a method for treating nickel-containing wastewater and its recycling. The present invention aims to solve the problem of the narrow adaptability of existing methods for treating nickel-containing wastewater. The present invention passes the nickel-containing wastewater through a primary mixing unit and then sends it into a diversion unit, and diverts it into high-salt wastewater, electroplating wastewater and metallurgical wastewater according to the conductivity, pH value and nickel ion concentration of the nickel-containing wastewater; the high-salt wastewater is treated by a reverse osmosis unit, the electroplating wastewater is treated by an ion exchange unit, and the metallurgical wastewater is treated by an adsorption treatment unit, and the different complex wastewaters obtained are jointly passed into a complex breaking and recovery unit, and after treatment, recovered nickel slag and reclaimed water are obtained. The method for treating nickel-containing wastewater provided by the present invention can treat multiple types of nickel-containing wastewater at the same time, and can achieve good treatment effects, and complete the recovery of nickel elements, and has good application value.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment, and particularly relates to a method for treating nickel-containing wastewater and recycling it. Background Art

[0002] Treatment of nickel-containing wastewater is a crucial component of modern industrial pollution prevention and control. Nickel, due to its widespread use in electroplating, stainless steel manufacturing, and battery production, has become a key pollutant in wastewater. Its toxicity and bioaccumulation pose a serious threat to the environment and human health. The primary sources of nickel-containing wastewater include cleaning processes during electroplating and electroless nickel plating. Nickel often forms stable complexes with ammonia nitrogen and organic chelating agents, significantly increasing the difficulty of wastewater treatment.

[0003] The traditional and commonly used method for treating nickel-containing wastewater is chemical precipitation, which uses hydroxide or sulfide as a precipitant to remove nickel by generating Ni(OH)2 or NiS precipitation. However, this method is sensitive to pH value and is not suitable for the treatment of nickel-containing wastewater in the complex system. 2+ The strong chelation makes it ineffective, and high-water content sludge is produced, leading to a surge in subsequent disposal costs. With technological advancements, ion exchange, adsorption, and membrane separation technologies have been introduced into the treatment of nickel-containing wastewater, forming a series of nickel-containing wastewater treatment processes based on multi-stage treatment, which has achieved significant progress. However, current nickel-containing wastewater treatment methods still have certain shortcomings in treatment efficiency and adaptability, making it difficult to achieve efficient and broad-spectrum nickel-containing wastewater treatment, and it is also difficult to recycle the large amount of nickel present in the wastewater.

[0004] At present, the narrow adaptability of existing nickel-containing wastewater treatment methods remains a major problem facing the industry.

[0005] Therefore, a method for treating nickel-containing wastewater and recycling the same is proposed. Summary of the Invention

[0006] The present invention aims to provide a method for treating and recycling nickel-containing wastewater. The method passes the nickel-containing wastewater through a primary mixing unit and then into a diversion unit, where the wastewater is divided into high-salt wastewater, electroplating wastewater, and metallurgical wastewater according to the conductivity, pH value, and nickel ion concentration of the wastewater. The high-salt wastewater is treated by a reverse osmosis unit, the electroplating wastewater is treated by an ion exchange unit, and the metallurgical wastewater is treated by an adsorption treatment unit. The first, second, and third complex wastewaters obtained are then passed through a complex breaking and recovery unit to obtain recovered nickel slag and reclaimed water.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A method for treating nickel-containing wastewater comprises the following steps:

[0009] The nickel-containing wastewater treated by the technical solution provided by the present invention comes from different processes, including high-salt wastewater, electroplating wastewater, and metallurgical wastewater. The present invention performs diversion treatment on different types of nickel-containing wastewater by online detection of multiple key data of the nickel-containing wastewater.

[0010] The nickel-containing wastewater is passed into the primary mixing unit and then into the diversion unit after treatment;

[0011] The working process of the primary mixing unit is as follows: the nickel-containing wastewater is passed into the mixing tank, stirred at a speed of 50-100 rpm for 60 minutes, passed through a filter with a mesh diameter of 1 mm, and then sent to the diversion unit.

[0012] The diversion unit includes: a conductivity detection unit, a pH value detection unit and a nickel ion concentration detection unit;

[0013] The diversion unit diverts nickel-containing wastewater into high-salt wastewater, electroplating wastewater and metallurgical wastewater based on the conductivity, pH value and nickel ion concentration of the nickel-containing wastewater;

[0014] Passing high-salt wastewater into a reverse osmosis unit to obtain enriched brine and first complexed wastewater;

[0015] Passing the electroplating wastewater into an ion exchange unit to obtain a second complex wastewater;

[0016] The metallurgical wastewater is passed through an adsorption treatment unit to obtain heavy metal wastewater and third complex wastewater;

[0017] The first complex wastewater, the second complex wastewater and the third complex wastewater are passed into a complex breaking and recovery unit to obtain recovered nickel slag and reclaimed water.

[0018] Preferably, the working process of the diversion unit is: detecting the conductivity of the nickel-containing wastewater passing through the primary mixing unit, and when the conductivity is higher than the conductivity threshold, outputting the nickel-containing wastewater as high-salt wastewater; when the conductivity is lower than the conductivity threshold, detecting the pH value of the nickel-containing wastewater, and when the pH value is lower than the pH threshold, outputting the nickel-containing wastewater as electroplating wastewater; when the pH value is higher than the pH threshold, detecting the nickel ion concentration of the nickel-containing wastewater, and if the nickel ion concentration is higher than the nickel ion concentration threshold, outputting the nickel-containing wastewater as metallurgical wastewater.

[0019] Preferably, the conductivity threshold is 10 ms / cm; the pH threshold is 8; and the nickel ion concentration threshold is 5 mg / L.

[0020] The core characteristic of high-salt wastewater is high electrical conductivity, in which nickel elements mainly exist in the form of ions and contain a large number of neutral inorganic salt ions; the core characteristic of electroplating wastewater is low pH value and low concentration of neutral inorganic salt ions, but there are other transition metal ions such as iron, copper, and cobalt, and the main form of nickel elements is complexes; the core characteristic of metallurgical wastewater is that it contains some organic impurities and heavy metal ions, and the main form of nickel elements is complexes, and some are ions.

[0021] Preferably, the working process of the reverse osmosis unit is: adding ferric chloride to the high-salt wastewater, using hydrochloric acid to adjust the pH value to 4-5, performing reverse osmosis treatment with a high-salt resistant reverse osmosis membrane at an operating temperature of 25°C and an operating pressure of 2-4MPa, and outputting enriched brine from the high-concentration side of the high-salt resistant reverse osmosis membrane and outputting the first complexed wastewater from the low-concentration side.

[0022] The amount of ferric chloride added is 0.2 wt% of the mass of the high-salt wastewater.

[0023] Preferably, the working process of the ion exchange unit is: passing the electroplating wastewater through a cationic chelating ion exchange resin at an operating flow rate of 5-10 BV / hour, and continuously adding a regenerant, wherein the amount of the regenerant added is 12 wt% of the mass of the electroplating wastewater.

[0024] The regeneration agent is a mixture of hydrochloric acid, disodium EDTA aqueous solution and saturated sodium chloride aqueous solution. The addition mass ratio of hydrochloric acid, disodium EDTA aqueous solution and saturated sodium chloride aqueous solution is 1:0.5:19, the concentration of hydrochloric acid is 1 mol / L, and the concentration of disodium EDTA aqueous solution is 0.5 mol / L.

[0025] Preferably, the working process of the adsorption treatment unit is: the metallurgical wastewater is passed into an activated carbon adsorption column, adsorbed at an operating pressure of 0.1-0.2MPa, and then passed into a modified zeolite adsorption column, adsorbed at an operating pressure of 200-350KPa to obtain a third complex wastewater; the activated carbon adsorption column and the modified zeolite adsorption column are rinsed with hydrochloric acid with a mass concentration of 1% to obtain heavy metal wastewater.

[0026] Among them, the average specific surface area of ​​activated carbon in the activated carbon adsorption column is 850m 2 / g; The preparation method of the modified zeolite used in the modified zeolite adsorption column is as follows: soaking the zeolite in a cationic surfactant solution for 12 hours, drying it, and then soaking it in a manganese nitrate solution for 24 hours, drying it again at 110°C for 24 hours, and calcining it at 500°C for 8 hours to obtain the modified zeolite.

[0027] The cationic surfactant solution is a 0.05 mol / L hexadecyltrimethylammonium bromide aqueous solution; and the concentration of the manganese nitrate solution is 0.78 mol / L.

[0028] Preferably, the working process of the complex breaking and recovery unit is: after mixing the first complex wastewater, the second complex wastewater and the third complex wastewater, using sulfuric acid to adjust the pH value to 1-1.5, adding potassium permanganate at an operating temperature of 40-45°C, maintaining a stirring speed of 300-500rpm and treating for 2 hours, lowering the reaction temperature to 30°C and adding a hydrogen peroxide solution, treating for 1 hour and adjusting the pH value, collecting the precipitate generated in the process of pH value from 2 to 4, that is, recovering nickel slag, continuing to adjust the pH value to 8, and filtering to obtain reclaimed water.

[0029] Among them, the addition amount of potassium permanganate is 0.7wt% of the total mass of the first complex wastewater, the second complex wastewater and the third complex wastewater, the addition amount of the hydrogen peroxide aqueous solution is 0.2wt% of the total mass of the first complex wastewater, the second complex wastewater and the third complex wastewater, and the concentration of the hydrogen peroxide aqueous solution is 20wt%.

[0030] A method for recycling nickel-containing wastewater, specifically, refining recovered nickel slag to obtain high-purity metallic nickel, and using the reclaimed water as circulating water for treating the nickel-containing wastewater.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] By online testing of key data such as conductivity, pH value and nickel ion concentration, nickel-containing wastewater can be accurately divided into high-salt wastewater, electroplating wastewater and metallurgical wastewater and treated accordingly, avoiding the inefficiency problem caused by using the same multi-stage treatment process for different wastewaters and improving the overall treatment efficiency and recovery effect.

[0033] Complex wastewater generated from different processes is centrally processed for complex decomposition and recovery. The pH is adjusted with sulfuric acid, the complexing agent is oxidized with potassium permanganate, and the excess potassium permanganate is reduced with hydrogen peroxide. Finally, nickel slag is precipitated and recovered. This centralized treatment streamlines the nickel recovery process, reduces processing costs, and improves nickel recovery rates.

[0034] In the ion exchange unit, a mixture of hydrochloric acid, disodium EDTA aqueous solution, and saturated sodium chloride aqueous solution is used as the regenerant. Hydrochloric acid provides an acidic environment, facilitating regeneration of the cation exchange resin; disodium EDTA acts as a complexing agent, helping to remove metal ions bound to the resin; and sodium chloride provides a high ionic strength environment, promoting the shift in ion exchange equilibrium. This combined regenerant design improves the regeneration efficiency of the ion exchange resin and extends its service life.

[0035] In the treatment of metallurgical wastewater, a two-stage adsorption process is employed: activated carbon adsorption and modified zeolite adsorption. The activated carbon primarily adsorbs organic impurities in the wastewater, while the modified zeolite adsorbs heavy metal ions. This multi-stage adsorption process effectively removes a variety of pollutants from metallurgical wastewater, improving effluent quality and reducing the difficulty of subsequent treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The figure is a process flow chart of the nickel-containing wastewater treatment method of the present invention. DETAILED DESCRIPTION

[0037] The technical solutions of the present invention are described clearly and completely below through some embodiments and experimental examples. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0038] Reference Figure 1 The process flow chart shown in the figure shows that the present invention provides a method for treating nickel-containing wastewater and recycling the same. The technical solution is as follows:

[0039] Example 1

[0040] High-salt wastewater is selected as nickel-containing wastewater. The core characteristic of high-salt wastewater is high conductivity, in which nickel elements mainly exist in the form of ions and contain a large amount of neutral inorganic salt ions.

[0041] The relevant physical parameters of high-salt wastewater are: density 1.07g / cm 3 , the inorganic salt content is 115g / L.

[0042] The nickel-containing wastewater was passed into the mixing tank, stirred at a speed of 50 rpm for 60 minutes, passed through a filter with a mesh diameter of 1 mm, and then sent to the diversion unit.

[0043] The conductivity of the nickel-containing wastewater passing through the primary mixing unit was detected to be 143.8ms / cm, which is higher than 10ms / cm. The nickel-containing wastewater was output as high-salt wastewater and sent to the reverse osmosis unit.

[0044] The working process of the reverse osmosis unit is: add ferric chloride to the high-salt wastewater, use hydrochloric acid to adjust the pH value to 4, and perform reverse osmosis treatment with a high-salt resistant reverse osmosis membrane at an operating temperature of 25°C and an operating pressure of 2MPa. The high-concentration side of the high-salt resistant reverse osmosis membrane outputs enriched brine, and the low-concentration side outputs the first complex wastewater.

[0045] The amount of ferric chloride added is 0.2 wt% of the mass of the high-salt wastewater.

[0046] The first complex wastewater was sent to the complex breaking and recovery unit, and the pH value was adjusted to 1 with sulfuric acid. Potassium permanganate was added at an operating temperature of 40°C and the stirring speed was maintained at 300 rpm. After treating for 2 hours, the reaction temperature was lowered to 30°C and a hydrogen peroxide solution was added. After treating for 1 hour, the pH value was adjusted. The precipitate generated in the process of pH value increasing from 2 to 4 was collected to recover nickel slag. The pH value was further adjusted to 8 and filtered to obtain reclaimed water.

[0047] Example 2

[0048] Electroplating wastewater is selected as nickel-containing wastewater. The core characteristics of electroplating wastewater are low pH value and low concentration of neutral inorganic salt ions, but there are other transition metal ions such as iron, copper, and cobalt. The main form of nickel element is complex.

[0049] The relevant physical parameters of electroplating wastewater are: density 1.02g / cm 3 The main types of complexing agents are EDTA and cyanide.

[0050] The nickel-containing wastewater was passed into the mixing tank, stirred at a speed of 70 rpm for 60 minutes, passed through a filter with a mesh diameter of 1 mm, and then sent to the diversion unit.

[0051] The conductivity of the nickel-containing wastewater passing through the primary mixing unit was detected to be 8.2 ms / cm, which is lower than 10 ms / cm. The pH value of the nickel-containing wastewater was detected to be 6.5, which is lower than 8. The nickel-containing wastewater was output as electroplating wastewater.

[0052] The electroplating wastewater is passed through a cationic chelating ion exchange resin at an operating flow rate of 5 BV / hour, and a regeneration agent is continuously added. The amount of the regeneration agent added is 12 wt % of the mass of the electroplating wastewater. After the treatment is completed, a second complex wastewater is output.

[0053] The regeneration agent is a mixture of hydrochloric acid, disodium EDTA aqueous solution and saturated sodium chloride aqueous solution. The addition mass ratio of hydrochloric acid, disodium EDTA aqueous solution and saturated sodium chloride aqueous solution is 1:0.5:19, the concentration of hydrochloric acid is 1 mol / L, and the concentration of disodium EDTA aqueous solution is 0.5 mol / L.

[0054] The second complex wastewater was sent to the complex breaking and recovery unit, and the pH value was adjusted to 1.5 with sulfuric acid. Potassium permanganate was added at an operating temperature of 45°C and the stirring speed was maintained at 500 rpm for 2 hours. The reaction temperature was lowered to 30°C and an aqueous hydrogen peroxide solution was added. After treating for 1 hour, the pH value was adjusted. The precipitate generated in the process of pH value increasing from 2 to 4 was collected to recover nickel slag. The pH value was further adjusted to 8 and filtered to obtain reclaimed water.

[0055] Example 3

[0056] Metallurgical wastewater is selected as nickel-containing wastewater. The core characteristics of metallurgical wastewater are that it contains some organic impurities and heavy metal ions. The main form of nickel element is complex and some is ions.

[0057] The relevant physical parameters of metallurgical wastewater are: density 1.01g / cm 3 , containing suspended matter and organic impurities.

[0058] The conductivity of the nickel-containing wastewater passing through the primary mixing unit was detected to be 6.4ms / cm, which is lower than 10ms / cm. The pH value of the nickel-containing wastewater was detected to be 8.7, which is greater than 8. The nickel ion concentration of the nickel-containing wastewater was detected to be 22.7mg / L, which is greater than 5mg / L. The nickel-containing wastewater is output as metallurgical wastewater.

[0059] The metallurgical wastewater is passed into an activated carbon adsorption column and adsorbed at an operating pressure of 0.1 MPa. It is then passed into a modified zeolite adsorption column and adsorbed at an operating pressure of 200 KPa to obtain a third complex wastewater. The activated carbon adsorption column and the modified zeolite adsorption column are rinsed with hydrochloric acid with a mass concentration of 1% to obtain heavy metal wastewater.

[0060] The third complex wastewater was sent to the complex breaking and recovery unit, and the pH value was adjusted to 1.1 with sulfuric acid. Potassium permanganate was added at an operating temperature of 42°C and the stirring speed was maintained at 350 rpm. After treating for 2 hours, the reaction temperature was lowered to 30°C and an aqueous hydrogen peroxide solution was added. After treating for 1 hour, the pH value was adjusted. The precipitate generated in the process of pH value increasing from 2 to 4 was collected to recover nickel slag. The pH value was further adjusted to 8 and filtered to obtain reclaimed water.

[0061] Examples 1-3 describe the general process for treating different types of wastewater. These processes are also followed when treating wastewater with different physical parameters.

[0062] Examples 4-20 differ from Examples 1-3 in terms of wastewater sources and operating parameters. Different process flows are adopted according to the wastewater parameters. The specific parameters are summarized in Tables 1 and 2.

[0063] Table 1. Sources of wastewater and changes in operating parameters in Examples 1-20 (I)

[0064] Wastewater sources Stirring speed of primary mixing unit (rpm) Reverse Osmosis Units Treat pH Reverse osmosis unit operating pressure (MPa) Ion exchange unit operating flow rate (BV / hour) Example 1 High-salt wastewater 50 4 2 - Example 2 Electroplating wastewater 70 - - 5 Example 3 Metallurgical wastewater 100 - - - Example 4 High-salt wastewater 63 5 4 - Example 5 Electroplating wastewater 72 - - 10 Example 6 Metallurgical wastewater 88 - - - Example 7 High-salt wastewater, electroplating wastewater 58 4.6 2.6 6.2 Example 8 Electroplating wastewater, metallurgical wastewater 95 - - 8.7 Example 9 High-salt wastewater 68 4.4 2.2 - Example 10 Metallurgical wastewater 77 - - - Example 11 High-salt wastewater, metallurgical wastewater 82 4.5 2.9 - Example 12 Electroplating wastewater 52 - - 8.2 Example 13 High-salt wastewater 90 4.3 2.7 - Example 14 Metallurgical wastewater 65 - - - Example 15 High-salt wastewater, electroplating wastewater 73 4.2 2.5 6.5 Example 16 Electroplating wastewater, metallurgical wastewater 85 - - 9.0 Example 17 High-salt wastewater 56 4.9 2.4 - Example 18 Metallurgical wastewater 92 - - - Example 19 High-salt wastewater, electroplating wastewater 60 4.3 2.8 7.2 Example 20 Electroplating wastewater 78 - - 6.8

[0065] Table 2 Changes in operating parameters of Examples 1-20 (II)

[0066] Activated carbon adsorption column operating pressure (MPa) Modified zeolite adsorption column operating pressure (KPa) pH value of the chelation recovery unit operation Operating temperature of network breaking and recovery unit (℃) Stirring speed of network breaking and recovery unit (rpm) Example 1 - - 1 40 300 Example 2 - - 1.5 45 500 Example 3 0.1 200 1.1 42 350 Example 4 - - 1.3 43 400 Example 5 - - 1.2 41 380 Example 6 0.2 350 1.4 44 450 Example 7 - - 1.05 40.5 320 Example 8 0.16 280 1.35 43.5 420 Example 9 - - 1.25 42.5 360 Example 10 0.17 350 1.15 41.5 340 Example 11 0.19 320 1.45 44.5 480 Example 12 - - 1.08 40.8 310 Example 13 - - 1.32 43.2 410 Example 14 0.135 235 1.22 42.2 370 Example 15 - - 1.18 41.8 330 Example 16 0.145 245 1.28 42.8 390 Example 17 - - 1.42 44.2 460 Example 18 0.115 215 1.06 40.6 305 Example 19 - - 1.12 41.2 345 Example 20 - - 1.48 44.8 490

[0067] Comparative Example 1

[0068] The difference from Example 1 is that the conductivity detection unit in the diversion unit is removed, and other process parameters are the same as those in Example 1.

[0069] Comparative Example 2

[0070] The difference from Example 2 is that the pH value detection unit in the diversion unit is removed, and the other process parameters are the same as those in Example 2.

[0071] Comparative Example 3

[0072] The difference from Example 3 is that the nickel ion concentration detection unit in the diversion unit is removed, and the other process parameters are the same as those in Example 3.

[0073] Comparative Example 4

[0074] The difference from Example 4 is that hydrochloric acid is used to adjust the pH value during the network breaking and recovery process, and the other process parameters are the same.

[0075] Comparative Example 5

[0076] The difference from Example 4 is that hydrogen peroxide is not added during the network breaking and recovery process, and other process parameters are the same.

[0077] Comparative Example 6

[0078] Different from Example 11, in the ion exchange unit, no saturated aqueous solution of sodium chloride was added as the regeneration agent, and other process parameters were the same.

[0079] Comparative Example 7

[0080] The difference from Example 11 is that the ion exchange resin is replaced by a weakly acidic anion exchange resin, and the other process parameters are the same.

[0081] Comparative Example 8

[0082] The difference from Example 16 is that the order of the activated carbon adsorption column and the modified zeolite adsorption column is exchanged, and the other process parameters are the same.

[0083] Comparative Example 9

[0084] The difference from Example 16 is that an ordinary zeolite adsorption column is used instead of the modified zeolite adsorption column, and other process parameters are the same.

[0085] Experimental Example 1

[0086] The purity of the recovered nickel slag and the nickel ion content in the treated water of Examples 1-3 and Comparative Examples 1-3 were tested, and the results are summarized in Table 3.

[0087] The purity of the recovered nickel slag is calculated as NiO and confirmed by EDTA titration after acid dissolution, and the result is expressed as a percentage.

[0088] The nickel ion content in the reclaimed water was determined by atomic absorption spectrometry, and the final result was expressed in mg / m3 express.

[0089] Table 3 Purity of recovered nickel slag and nickel ion content in reclaimed water after treatment in Examples 1-3 and Comparative Examples 1-3

[0090] Purity of recovered nickel slag (as NiO, wt%) <![CDATA[Content of nickel ions in reclaimed water (mg / m 3 )]]> Example 1 77.2 31.7 Example 2 73.8 21.1 Example 3 71.6 25.9 Comparative Example 1 62.7 223.8 Comparative Example 2 57.3 86.4 Comparative Example 3 26.4 109.1

[0091] As shown in the data of Table 3, Examples 1-3 all use complete shunt units, and different types of nickel-containing wastewater are treated accordingly according to the process design provided by the present invention. The purity of the recovered nickel slag obtained is relatively high, and the nickel ion content in the reclaimed water is low, so it can be directly reused without causing waste. Comparative Example 1 removes the conductivity detection unit, and high-salt wastewater is not targeted for treatment. The pH value of high-salt wastewater is greater than 8, and nickel ions exist mainly in ionic form, so it is sent to the adsorption treatment unit. The large amount of neutral inorganic salt ions contained therein significantly affect the treatment effect of the adsorption treatment unit, resulting in a decrease in the purity of the recovered nickel slag and a significant increase in the nickel ion content in the reclaimed water. Comparative Example 2 removes the pH detection unit, resulting in the electroplating wastewater being shunted to the adsorption treatment unit for treatment, with significantly worse results. Comparative Example 3 removes the nickel ion concentration detection unit, resulting in the metallurgical wastewater being unable to be sent to the adsorption treatment unit, but entering the ion exchange unit, and the treatment effect and recovery effect are significantly reduced. In summary, accurate shunting and targeted pretreatment are the keys to improving nickel recovery efficiency. By online testing of key data such as conductivity, pH value and nickel ion concentration, nickel-containing wastewater can be accurately divided into high-salt wastewater, electroplating wastewater and metallurgical wastewater and treated accordingly, avoiding the inefficiency problem caused by using the same multi-stage treatment process for different wastewaters and improving the overall treatment efficiency and recovery effect.

[0092] Experimental Example 2

[0093] The purity of the recovered nickel slag and the nickel ion content in the treated water of Example 4-10 and Comparative Example 4-5 were tested, and the results are summarized in Table 4.

[0094] Table 4 Purity of recovered nickel slag and nickel ion content in reclaimed water after treatment in Example 4-10 and Comparative Example 4-5

[0095] Purity of recovered nickel slag (as NiO, wt%) <![CDATA[Nickel ion content in reclaimed water (mg / m 3 )]]> Example 4 74.5 28.3 Example 5 72.1 24.0 Example 6 76.0 30.5 Example 7 73.0 22.5 Example 8 75.2 27.8 Example 9 71.9 26.1 Example 10 74.8 23.4 Comparative Example 4 64.2 31.5 Comparative Example 5 49.9 71.0

[0096] As shown in the data of Table 4, although Examples 4-10 and 1-3 are different in wastewater source and operating parameters, after taking corresponding process treatment, the recovered nickel slag purity of gained is higher, and the nickel ion content of reclaimed water is lower, which meets the treatment requirements. Comparative Example 4 introduces a large amount of chloride ions that reduce the effect of potassium permanganate oxidant due to the use of hydrochloric acid to adjust the pH value, resulting in incomplete chelation treatment, and the purity of the recovered nickel slag is reduced, and the nickel ion content in the reclaimed water is slightly increased. Comparative Example 5 does not reduce excessive potassium permanganate by means of the effect of hydrogen peroxide, resulting in the process of regulating pH precipitation, and part of the manganese element also produces precipitation, and the recovery of nickel slag purity is reduced. In summary, potassium permanganate is utilized to oxidize the chelating agent, and then excessive potassium permanganate is reduced with hydrogen peroxide, and finally precipitated and recovered nickel slag, and this centralized treatment method simplifies the nickel recovery process, reduces processing costs, and simultaneously improves the recovery rate of nickel.

[0097] Experimental Example 3

[0098] The purity of the recovered nickel slag and the nickel ion content in the treated water of Examples 11-15 and Comparative Examples 6-7 were tested, and the results are summarized in Table 5.

[0099] Table 5 Purity of recovered nickel slag and nickel ion content in reclaimed water after treatment in Examples 11-15 and Comparative Examples 6-7

[0100] Purity of recovered nickel slag (as NiO, wt%) <![CDATA[The nickel ion content in reclaimed water (mg / m 3 )]]> Example 11 72.5 29.1 Example 12 75.8 20.9 Example 13 73.5 25.5 Example 14 74.2 27.0 Example 15 72.8 21.8 Comparative Example 6 56.2 67.3 Comparative Example 7 68.4 92.9

[0101] As shown in the data of Table 5, Examples 11-15 can achieve good treatment effects when treating different wastewaters, with high purity of recovered nickel slag and low nickel ion content in reclaimed water. In Comparative Example 6, because no saturated aqueous solution of sodium chloride is added to the regeneration agent, the system lacks the function of regulating ionic strength, the metal ion desorption rate decreases, and the accumulation of metals remaining on the resin surface causes the exchange capacity to decay. Comparative Example 7 uses a weakly acidic anion resin, whose functional groups have poor compatibility with the acidic environment of the composite regeneration agent and cannot achieve effective regeneration, which reversely verifies the compatibility of the ternary regeneration agent with a specific resin type. In summary, hydrochloric acid, disodium EDTA aqueous solution and saturated aqueous solution of sodium chloride are used as regeneration agents, and the three form a complementary functional system. Hydrochloric acid plays a dual role in the system: providing an acidic environment to promote the dissociation of the sulfonic acid groups of the cation exchange resin and generate active site H + The acidic condition also promotes the deprotonation reaction of disodium EDTA, making it more efficient with Ni 2+ 、Fe 3+ The addition of sodium chloride drives the ion exchange equilibrium to move through the ionic strength effect. +Competitive binding with the active sites of the resin forces the metal cations attached to the resin surface to desorb into the liquid phase, while forming soluble compounds such as nickel chloride to avoid secondary precipitation. This synergistic effect not only improves the ion exchange effect, but also improves the efficiency of continuous wastewater treatment, thereby comprehensively improving the treatment and recovery effects of the nickel-containing wastewater treatment process.

[0102] Experimental Example 4

[0103] The purity of the recovered nickel slag and the nickel ion content in the treated water of Examples 16-20 and Comparative Examples 8-9 were tested, and the results are summarized in Table 6.

[0104] Table 6 Purity of recovered nickel slag and nickel ion content in reclaimed water after treatment in Examples 16-20 and Comparative Examples 8-9

[0105] Purity of recovered nickel slag (as NiO, wt%) <![CDATA[The nickel ion content in reclaimed water (mg / m 3 )]]> Example 16 76.2 31.2 Example 17 71.7 24.7 Example 18 74.0 29.8 Example 19 73.3 22.9 Example 20 75.5 26.8 Comparative Example 8 53.0 105.2 Comparative Example 9 62.6 37.9

[0106] As shown in the data of Table 6, the treatment effect of embodiment 16-20 is similar to embodiment 1-15, and the relative stability of reclaiming nickel slag purity and midwater nickel ion content is maintained under different wastewater sources and operating parameters.Comparative Example 8 is owing to having exchanged the sequence of activated carbon adsorption column and modified zeolite adsorption column, so that organic matter rapidly occupies the adsorption site of zeolite, reduces its adsorption capacity to heavy metal ions, and simultaneously, macromolecular organic matter can block the pore of zeolite, causes adsorption column to lose efficacy, causes the substantial decline of final treatment effect.Comparative Example 9 is owing to using unmodified zeolite to fill in adsorption column, and the adsorption effect of other ions beyond nickel ion significantly declines, causes foreign ion content in the third complex wastewater to rise, thus causes the decline of final reclaiming nickel slag purity. In summary, the two-stage adsorption process of activated carbon and modified zeolite has been optimized for the organic impurities and heavy metal ions contained in metallurgical wastewater. The activated carbon is used to remove organic impurities and colloidal substances in advance, and the modified zeolite adsorption column is used to adsorb heavy metal ions in a targeted manner. This significantly reduces the process complexity of subsequent decomposition treatment, improves the purity of the recovered nickel slag, and ensures a low nickel ion content in the reclaimed water.

[0107] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for treating nickel-containing wastewater, characterized in that: The processing method is as follows: The nickel-containing wastewater is passed into the primary mixing unit and then into the diversion unit after treatment; The diversion unit includes: a conductivity detection unit, a pH value detection unit and a nickel ion concentration detection unit; The working process of the diversion unit is as follows: detecting the conductivity of the nickel-containing wastewater passing through the primary mixing unit, and when the conductivity is higher than 10ms / cm, outputting the nickel-containing wastewater as high-salt wastewater; when the conductivity is lower than 10ms / cm, detecting the pH value of the nickel-containing wastewater, and when the pH value is lower than 8, outputting the nickel-containing wastewater as electroplating wastewater; when the pH value is higher than 8, detecting the nickel ion concentration of the nickel-containing wastewater, and if the nickel ion concentration is higher than 5mg / L, outputting the nickel-containing wastewater as metallurgical wastewater; Passing the high-salt wastewater into a reverse osmosis unit and performing reverse osmosis treatment with a high-salt resistant reverse osmosis membrane, wherein the high-concentration side of the high-salt resistant reverse osmosis membrane outputs enriched brine and the low-concentration side outputs the first complex wastewater; The electroplating wastewater is passed through an ion exchange unit, nickel ions are enriched by a chelating ion exchange resin, and then eluted with a regeneration agent to obtain a second complex wastewater; The metallurgical wastewater is passed through an adsorption treatment unit, and sequentially passed through an activated carbon adsorption column and a modified zeolite adsorption column to obtain a third complex wastewater; The first complex wastewater, the second complex wastewater and the third complex wastewater are passed into a complex breaking and recovery unit to obtain recovered nickel slag and reclaimed water.

2. A method for treating nickel-containing wastewater according to claim 1, characterized in that: The working process of the primary mixing unit is as follows: the nickel-containing wastewater is passed into the mixing tank, stirred at a speed of 50-100 rpm for 60 minutes, passed through a filter with a mesh diameter of 1 mm, and then sent to the diversion unit.

3. A method for treating nickel-containing wastewater according to claim 1, characterized in that: The working process of the reverse osmosis unit is: adding ferric chloride to the high-salt wastewater, adjusting the pH value to 4-5 with hydrochloric acid, and performing reverse osmosis treatment at an operating temperature of 25° C. and an operating pressure of 2-4 MPa.

4. A method for treating nickel-containing wastewater according to claim 1, characterized in that: The working process of the ion exchange unit is: the electroplating wastewater is passed through the chelating ion exchange resin at an operating flow rate of 5-10BV / hour, and the regeneration agent is continuously added. The amount of the regeneration agent added is 12wt% of the mass of the electroplating wastewater. After the treatment is completed, the second complex wastewater is output.

5. A method for treating nickel-containing wastewater according to claim 1, characterized in that: The working process of the adsorption treatment unit is as follows: the metallurgical wastewater is passed into an activated carbon adsorption column, adsorbed at an operating pressure of 0.1-0.2 MPa, and then passed into a modified zeolite adsorption column, adsorbed at an operating pressure of 200-350 KPa to obtain the third complex wastewater; the activated carbon adsorption column and the modified zeolite adsorption column are rinsed with hydrochloric acid with a mass concentration of 1% to obtain heavy metal wastewater.

6. A method for treating nickel-containing wastewater according to claim 5, characterized in that: The preparation method of the modified zeolite in the modified zeolite adsorption column is as follows: soaking the zeolite in a cationic surfactant solution, drying it, soaking it in a manganese nitrate solution, drying it again, and calcining it to obtain the modified zeolite.

7. A method for treating nickel-containing wastewater according to claim 1, characterized in that: The working process of the complex breaking and recovery unit is as follows: after mixing the first complex wastewater, the second complex wastewater and the third complex wastewater, using sulfuric acid to adjust the pH value to 1-1.5, adding potassium permanganate at an operating temperature of 40-45°C, maintaining a stirring speed of 300-500 rpm, and treating for 2 hours, lowering the reaction temperature to 30°C and adding a hydrogen peroxide solution, treating for 1 hour, and then adjusting the pH value, collecting the precipitate generated in the process of the pH value increasing from 2 to 4, that is, recovering the nickel slag, and further adjusting the pH value to 8, and filtering to obtain the reclaimed water.

8. A method for recycling nickel-containing wastewater, characterized in that: The recycling method comprises the following steps: refining the recovered nickel slag to obtain high-purity metallic nickel, and using the reclaimed water as circulating water for treating nickel-containing wastewater; the recovered nickel slag and the reclaimed water are obtained by treating the nickel-containing wastewater according to claim 1.

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