Treatment method and recycling of nickel-containing wastewater

Abstract

The invention belongs to the technical field of wastewater treatment, and particularly relates to a treatment method and recycling of nickel-containing wastewater. The invention aims to solve the problem of narrow application range of the existing nickel-containing wastewater treatment method. The method comprises the following steps: feeding nickel-containing wastewater into a shunting unit after passing through a primary mixing unit, and shunting the nickel-containing wastewater into high-salinity wastewater, electroplating wastewater and metallurgical wastewater according to the conductivity, pH value and nickel ion concentration of the nickel-containing wastewater; high-salinity wastewater is treated through a reverse osmosis unit, electroplating wastewater is treated through an ion exchange unit, metallurgical wastewater is treated through an adsorption treatment unit, obtained different complex wastewater is jointly introduced into a complex breaking and recycling unit, and recycled nickel slag and reclaimed water are obtained after treatment. The nickel-containing wastewater treatment method provided by the invention can treat various types of nickel-containing wastewater at the same time, can achieve a good treatment effect, completes recovery of the nickel element, and has a good application value.

Description

Technical Field

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

[0002] The treatment of nickel-containing wastewater is an important part of modern industrial pollution prevention and control. Nickel has become a key pollutant in wastewater due to its wide application in electroplating, stainless steel manufacturing and battery production, and its toxicity and bioaccumulation pose a serious threat to the environment and human health. The main sources of nickel-containing wastewater include the electroplating process cleaning process and the chemical nickel plating process, in which nickel often forms stable complexes with ammonia nitrogen, organic chelating agents, etc., which significantly increases the difficulty of wastewater treatment.

[0003] The traditional method for treating nickel-containing wastewater is chemical precipitation, which uses hydroxide or sulfide as a precipitant to generate Ni(OH) 2 Or NiS precipitation to achieve removal, but this method is sensitive to pH value, and in the complex system due to Ni 2+ The nickel-containing wastewater is ineffective due to strong chelation, and produces sludge with high water content, which leads to a surge in subsequent disposal costs. With the advancement of technology, 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, and significant progress has been made. However, the current nickel-containing wastewater treatment methods still have certain defects 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 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 its recycling are proposed. Summary of the invention

[0006] The object of the present invention is to provide a method for treating nickel-containing wastewater and its recycling. The present invention sends the nickel-containing wastewater to a diversion unit after passing through a primary mixing unit, and diverts the nickel-containing wastewater 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 first complex wastewater, the second complex wastewater and the third complex wastewater obtained respectively are introduced into a complex breaking recovery unit, and the recovered nickel slag and reclaimed water are obtained after treatment.

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

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

[0009] The nickel-containing wastewater treated by the technical solution provided by the present invention comes from different process, 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 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, and then passed through a filter with a mesh diameter of 1 mm and sent to the diversion unit.

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

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

[0014] Passing high-salinity 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 into 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 conductivity, in which nickel element mainly exists in the form of ions and contains a large amount of neutral inorganic salt ions; the core characteristic of electroplating wastewater is low pH value, low concentration of neutral inorganic salt ions, but the presence of other transition metal ions such as iron, copper, and cobalt, and the main form of nickel element is complex; the core characteristic of metallurgical wastewater is that it contains some organic impurities and heavy metal ions, and the main form of nickel element is complex, and some is ions.

[0021] Preferably, the working process of the reverse osmosis unit is: adding ferric chloride to 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 complex wastewater from the low-concentration side.

[0022] The added amount of ferric chloride is 0.2wt% 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 regeneration agent, wherein the amount of the regeneration agent added is 12 wt% of the mass of the electroplating wastewater.

[0024] Among them, the regeneration agent is a mixture of hydrochloric acid, disodium EDTA aqueous solution and saturated sodium chloride aqueous solution, the added 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, and adsorbed at an operating pressure of 0.1-0.2MPa, and then passed into a modified zeolite adsorption column, and 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, soaking it in a manganese nitrate solution for 24 hours after drying, 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 for 2 hours, lowering the reaction temperature to 30°C and adding a hydrogen peroxide solution, adjusting the pH value after 1 hour of treatment, 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 obtaining reclaimed water after filtering.

[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 includes refining the 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] 1. Through online detection 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] 2. The complex wastewater produced by different processes is uniformly broken and recovered. The pH value is adjusted by sulfuric acid, the complexing agent is oxidized by potassium permanganate, and then the excess potassium permanganate is reduced by hydrogen peroxide, and finally the nickel slag is precipitated and recovered. This centralized treatment method simplifies the nickel recovery process, reduces the treatment cost, and improves the nickel recovery rate.

[0034] 3. In the ion exchange unit, a mixture of hydrochloric acid, disodium EDTA aqueous solution and saturated sodium chloride aqueous solution is used as a regeneration agent. Hydrochloric acid provides an acidic environment, which is conducive to the regeneration of cation exchange resin; disodium EDTA acts as a complexing agent, which helps to remove metal ions bound to the resin; sodium chloride provides a high ionic strength environment to promote the movement of ion exchange equilibrium. This design of a compound regeneration agent improves the regeneration efficiency of the ion exchange resin and extends the service life of the resin.

[0035] 4. In the process of treating metallurgical wastewater, a two-stage adsorption process of activated carbon adsorption and modified zeolite adsorption is adopted. Activated carbon is mainly used to adsorb organic impurities in wastewater, and modified zeolite is used to adsorb heavy metal ions. This multi-stage adsorption process can effectively remove various pollutants in metallurgical wastewater, improve the effluent quality, and reduce the difficulty of subsequent treatment. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

[0039] Example 1

[0040] High-salt wastewater is selected as the nickel-containing wastewater. 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 amount of neutral inorganic salt ions.

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

[0042] The nickel-containing wastewater was passed into a 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 a diversion unit.

[0043] The conductivity of the nickel-containing wastewater passing through the primary mixing unit was detected to be 143.8 ms / cm, which is higher than 10 ms / 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 added amount of ferric chloride is 0.2wt% of the mass of the high-salt wastewater.

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

[0047] Example 2

[0048] Electroplating wastewater is selected as the 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 a 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 a diversion unit.

[0051] The conductivity of the nickel-containing wastewater passing through the primary mixing unit is detected to be 8.2 ms / cm, which is lower than 10 ms / cm. The pH value of the nickel-containing wastewater is detected to be 6.5, which is lower than 8. The nickel-containing wastewater is 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, wherein 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] Among them, the regeneration agent is a mixture of hydrochloric acid, disodium EDTA aqueous solution and saturated sodium chloride aqueous solution, the added 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 is sent to the complex breaking and recovery unit, and the pH value is adjusted to 1.5 with sulfuric acid. Potassium permanganate is added at an operating temperature of 45°C, and the stirring speed is maintained at 500rpm. After treating for 2 hours, the reaction temperature is lowered to 30°C and an aqueous hydrogen peroxide solution is added. After treating for 1 hour, the pH value is adjusted, and the precipitate generated in the process of pH value increasing from 2 to 4 is collected to recover nickel slag. The pH value is further adjusted to 8 and filtered to obtain reclaimed water.

[0055] Example 3

[0056] Metallurgical wastewater is selected as the 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 ion.

[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, adsorbed at an operating pressure of 0.1 MPa, and then passed into a modified zeolite adsorption column, 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 is sent to the complex breaking and recovery unit, and the pH value is adjusted to 1.1 with sulfuric acid. Potassium permanganate is added at an operating temperature of 42°C, and the stirring speed is maintained at 350rpm. After treating for 2 hours, the reaction temperature is lowered to 30°C and an aqueous hydrogen peroxide solution is added. After treating for 1 hour, the pH value is adjusted, and the precipitate produced in the process of pH value increasing from 2 to 4 is collected to recover nickel slag. The pH value is further adjusted to 8 and filtered to obtain reclaimed water.

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

[0062] Examples 4-20 differ from Examples 1-3 in 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 Variation of wastewater sources and operating parameters in Examples 1-20 (I)

[0064]

[0065]

[0066] Table 2 Variation of operating parameters of Examples 1-20 (II)

[0067]

[0068]

[0069] Comparative Example 1

[0070] 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.

[0071] Comparative Example 2

[0072] 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.

[0073] Comparative Example 3

[0074] 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.

[0075] Comparative Example 4

[0076] The difference from Example 4 is that hydrochloric acid is used to adjust the pH value during the chelation recovery process, and the other process parameters are the same.

[0077] Comparative Example 5

[0078] 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.

[0079] Comparative Example 6

[0080] Different from Example 11, in the ion exchange unit, the regeneration agent is not added with a saturated aqueous solution of sodium chloride, and the other process parameters are the same.

[0081] Comparative Example 7

[0082] 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.

[0083] Comparative Example 8

[0084] 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.

[0085] Comparative Example 9

[0086] The difference from Example 16 is that a common zeolite adsorption column is used instead of a modified zeolite adsorption column, and other process parameters are the same.

[0087] Experimental Example 1

[0088] The purity of the recovered nickel slag and the content of nickel ions in the reclaimed water after treatment in Examples 1-3 and Comparative Examples 1-3 were tested, and the results are summarized in Table 3.

[0089] 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.

[0090] The nickel ion content in the reclaimed water was determined by atomic absorption spectrometry, and the final result was expressed in mg / m 3 express.

[0091] Table 3 Purity of recovered nickel slag and nickel ion content in reclaimed water after treatment of Examples 1-3 and Comparative Examples 1-3

[0092]

[0093] 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 given 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 does not treat the high-salt wastewater in a targeted manner. The pH value of the high-salt wastewater is greater than 8, and the nickel ions mainly exist in the form of ions, so they are sent to the adsorption treatment unit, and 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, and the effect is significantly worse. 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 detection of key data such as conductivity, pH value and nickel ion concentration, nickel-containing wastewater can be accurately diverted 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.

[0094] Experimental Example 2

[0095] The purity of the recovered nickel slag and the content of nickel ions in the reclaimed water after treatment in Example 4-10 and Comparative Example 4-5 were tested, and the results are summarized in Table 4.

[0096] Table 4 Purity of recovered nickel slag and nickel ion content in reclaimed water after treatment of Example 4-10 and Comparative Example 4-5

[0097]

[0098]

[0099] As shown in the data of Table 4, although Examples 4-10 and Examples 1-3 differ in wastewater sources and operating parameters, after the corresponding process treatment is adopted, the obtained recovered nickel slag has a higher purity, and the nickel ion content of the reclaimed water is lower, which meets the treatment requirements. Comparative Example 4 uses hydrochloric acid to adjust the pH value, and introduces a large amount of chloride ions to reduce the effect of potassium permanganate oxidant, resulting in incomplete chelation treatment, reduced purity of recovered nickel slag, and slightly increased nickel ion content in reclaimed water. Comparative Example 5 does not reduce excess potassium permanganate with the help of hydrogen peroxide, resulting in the process of adjusting pH precipitation, and part of the manganese element also produces precipitation, and the purity of recovered nickel slag is reduced. In summary, potassium permanganate is used to oxidize the chelating agent, and then excess potassium permanganate is reduced with hydrogen peroxide, and finally precipitated to recover nickel slag. This centralized treatment method simplifies the nickel recovery process, reduces the processing cost, and improves the recovery rate of nickel.

[0100] Experimental Example 3

[0101] The purity of the recovered nickel slag and the content of nickel ions in the reclaimed water after treatment in Examples 11-15 and Comparative Examples 6-7 were tested, and the results are summarized in Table 5.

[0102] Table 5 Purity of recovered nickel slag and nickel ion content in reclaimed water after treatment of Examples 11-15 and Comparative Examples 6-7

[0103]

[0104] 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 desorption rate of metal ions decreases, and the accumulation of metals remaining on the surface of the resin 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 easily 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.

[0105] Experimental Example 4

[0106] The purity of the recovered nickel slag and the content of nickel ions in the reclaimed water after treatment in Examples 16-20 and Comparative Examples 8-9 were tested, and the results are summarized in Table 6.

[0107] Table 6 Purity of recovered nickel slag and nickel ion content in reclaimed water after treatment of Examples 16-20 and Comparative Examples 8-9

[0108]

[0109] As shown in the data of Table 6, the treatment effects of Examples 16-20 are similar to those of Examples 1-15, and the relative stability of the purity of the recovered nickel slag and the nickel ion content in the water is maintained under different wastewater sources and operating parameters. Comparative Example 8, due to the exchange of the sequence of the activated carbon adsorption column and the modified zeolite adsorption column, allows organic matter to rapidly occupy the adsorption sites of the zeolite, reducing its adsorption capacity for heavy metal ions. At the same time, macromolecular organic matter can block the pores of the zeolite, causing the adsorption column to fail, resulting in a significant decrease in the final treatment effect. Comparative Example 9, due to the use of unmodified zeolite to fill the adsorption column, the adsorption effect of other ions other than nickel ions is significantly reduced, causing the content of impurity ions in the third complex wastewater to increase, thereby resulting in a decrease in the purity of the final recovered nickel slag. 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 organic impurities and colloidal substances are removed in advance by activated carbon, and the heavy metal ions are adsorbed in a targeted manner by the modified zeolite adsorption column, which significantly reduces the process complexity of subsequent decomposition treatment, improves the purity of the recovered nickel slag, and ensures that the nickel ion content in the reclaimed water is low.

[0110] Although 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 the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present 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 shunt unit includes: a conductivity detection unit, a pH value detection unit and a nickel ion concentration detection unit; The conductivity detection unit outputs the nickel-containing wastewater with a conductivity higher than 10 ms / cm as high-salt wastewater; The pH value detection unit outputs the nickel-containing wastewater with a pH value lower than 8 as electroplating wastewater; The nickel ion concentration detection unit outputs nickel-containing wastewater with a nickel ion concentration higher than 5 mg / L 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 salt water, and the low-concentration side outputs the first complex wastewater; The electroplating wastewater is passed through an ion exchange unit, and 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 introduced 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: the nickel-containing wastewater is passed into a mixing tank, stirred at a rotation 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 diversion unit is: 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 the 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 the 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 the metallurgical wastewater.

4. 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.

5. 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, and the addition amount of the regeneration agent is 12wt% of the mass of the electroplating wastewater. After the treatment is completed, the second complex wastewater is output.

6. A method for treating nickel-containing wastewater according to claim 1, characterized in that: 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 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.

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

8. 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 300-500rpm for 2 hours, lowering the reaction temperature to 30°C and adding a hydrogen peroxide solution, adjusting the pH value after 1 hour of treatment, 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 obtaining the reclaimed water after filtering.

9. A method for recycling nickel-containing wastewater, characterized in that: The recycling method is: 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.

Images