Method for comprehensive treatment of titanium dioxide waste acid and electroplating nickel recovery liquid

Abstract

The application provides a method for comprehensive treatment of titanium dioxide waste acid and electroplating nickel recovery liquid, comprising the following steps: S1. treating the titanium dioxide waste acid to separate sulfuric acid; S2. treating the electroplating nickel recovery liquid to separate nickel salt; S3. reacting the sulfuric acid obtained in step S1 with the nickel salt obtained in step S2 to obtain nickel sulfate. The titanium dioxide waste acid and the nickel-containing recovery liquid are comprehensively treated for the first time, the sulfuric acid obtained by treating the titanium dioxide waste acid is used as a raw material for treating the nickel-containing recovery liquid, resources are saved, waste utilization is realized, the pressure of treating the waste acid in the titanium dioxide factory is reduced, and better economic and environmental benefits are obtained.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of industrial wastewater treatment, and particularly relates to a method for comprehensive treatment of titanium dioxide waste acid and electroplating nickel recovery liquid. BACKGROUND

[0002] Industrial production processes generate a large amount of waste acid and heavy metal wastewater, causing environmental pollution and resource waste. The waste acid generated in the production of titanium dioxide by the sulfuric acid method is currently the largest source of waste sulfuric acid in China, and if it is discharged and disposed of indiscriminately, it will cause great harm to the environment in China.

[0003] Electroplating generally refers to a process of decorating, protecting and obtaining certain new properties on the surface of metals and non-metals by using electrochemical methods. The nickel layer obtained by chemical plating has advantages such as high corrosion resistance and high wear resistance compared with traditional electroplating technology, and is widely used in petroleum chemical industry, electronics, machinery, aviation and other fields. The nickel compounds in large amounts in electroplating nickel wastewater are easily absorbed by the skin, have carcinogenicity and can cause degeneration of the nervous system of the human body, and at the same time, these heavy metals have high recycling value. The electroplating nickel recovery liquid obtained by membrane recovery treatment still contains a high concentration of organic matter and a small amount of inorganic impurities, which will affect the electroplating quality of nickel, such as causing pinholes and peeling of the layer, and further purification is required.

[0004] In the prior art, the titanium dioxide waste acid and the electroplating nickel recovery liquid are treated separately, and the waste is not fully utilized. At the same time, the existing methods for deep purification of electroplating nickel recovery liquid mainly include activated carbon adsorption, chemical oxidation, chemical precipitation and electrodialysis. The activated carbon adsorption method has good adsorption performance and can adsorb organic matter in the recovery liquid, but cannot remove the small amount of other metal ions remaining in the recovery liquid, and the adsorption carrier is difficult to handle. The chemical oxidation method and the chemical precipitation method need to introduce chemicals, which may cause additional pollution, and there is a reversible reaction. The electrodialysis method can effectively separate the organic matter in the nickel electroplating recovery liquid, but small-molecule organic matter with positive charge also enters the concentration chamber, resulting in insufficient purity of the nickel sulfate obtained by separation, and the existence of organic impurities affects the plating effect when reused. The Chinese patent document with publication number CN1504429A discloses a chemical electrodialysis method for combined treatment of electroplating wastewater, which combines chemical method and electrodialysis technology. It is to treat the electroplating wastewater by chemical method first, and then by electrodialysis. This method can reduce the use of oxidizing reagents by 40%, the use of reducing reagents by 50%, and the amount of electroplating sludge by 50% compared with the traditional chemical method for treating electroplating wastewater. However, in the electrodialysis treatment of this method, part of the organic matter with positive charge may penetrate the cation exchange membrane, thereby affecting the electroplating effect. SUMMARY

[0005] The technical problem solved by the present application is to provide a method for comprehensive treatment of titanium dioxide waste acid and nickel electroplating recovery liquid, and the sulfuric acid obtained by treating the titanium dioxide waste acid is used for the treatment of the nickel electroplating recovery liquid, so that the waste is comprehensively treated, and the problem of the insufficient purity of the separated nickel sulfate caused by the small-molecule positively charged organic substances entering the concentration chamber is solved.

[0006] To solve the above problems, the present application provides a method for comprehensive treatment of titanium dioxide waste acid and nickel electroplating recovery liquid, comprising the following steps:

[0007] S1. treating the titanium dioxide waste acid to separate sulfuric acid;

[0008] S2. treating the nickel electroplating recovery liquid to separate nickel salt;

[0009] S3. reacting the sulfuric acid obtained in step S1 with the nickel salt obtained in step S2 to obtain nickel sulfate.

[0010] Preferably, the nickel sulfate obtained in step S3 is crystallized to obtain nickel sulfate crystals.

[0011] Preferably, in step S1, a monovalent and divalent cation separation membrane electrodialysis system is used.

[0012] The monovalent and divalent cation separation membrane electrodialysis system comprises a first anode plate, a first anion exchange membrane, a monovalent and divalent cation separation membrane, and a first cathode plate; the first anion exchange membrane and the monovalent and divalent cation separation membrane are each provided in at least one group, and the first anion exchange membrane and the monovalent and divalent cation separation membrane are alternately arranged between the first anode plate and the first cathode plate; a first feed chamber is formed between the first anion exchange membrane and the monovalent and divalent cation separation membrane, and the titanium dioxide waste acid is introduced into the first feed chamber for treatment.

[0013] Preferably, the monovalent and divalent cation separation membrane is a polyethyleneimine modified membrane.

[0014] Preferably, when the monovalent and divalent cation separation membrane electrodialysis system is used for treatment, the current density is 6-50 mA / cm 2 .

[0015] Preferably, in step S2, a polymer-coated membrane electrodialysis system is used; and step S3 specifically comprises using the sulfuric acid obtained in step S1 as a stripping liquid of the polymer-coated membrane electrodialysis system.

[0016] The polymer-coated membrane electrodialysis system comprises a second anode plate, a second anion exchange membrane, a polymer-coated membrane, a third anion exchange membrane, a cation exchange membrane and a second cathode plate; wherein the second anion exchange membrane, the polymer-coated membrane, the third anion exchange membrane and the cation exchange membrane are sequentially arranged to form a repeating unit, and at least one set of the repeating unit is arranged between the second anode plate and the second cathode plate;

[0017] The second anion exchange membrane and the polymer-coated membrane form a second feed chamber, and the third anion exchange membrane and the cation exchange membrane form an acid feeding chamber, the electroplating nickel recovery liquid is fed into the second feed chamber for treatment, and the sulfuric acid obtained in step S1 is fed into the acid feeding chamber as a stripping liquid.

[0018] Preferably, the polymer-coated membrane comprises a base polymer and a carrier.

[0019] The base polymer is one or a combination of polyvinylidene fluoride resin or modified resin thereof, polyvinyl chloride resin or modified resin thereof, cellulose triacetate resin or modified resin thereof, and polytetrafluoroethylene resin or modified resin thereof.

[0020] The carrier is an extractant.

[0021] Preferably, the extractant is a tung oil-based extractant.

[0022] Preferably, the current density of the polymer-coated membrane electrodialysis system during treatment is 10-40 mA / cm 2 .

[0023] Preferably, in step S3, the concentration of the sulfuric acid is 0.1-0.5 mol / L.

[0024] Compared with the prior art, the present application has the following beneficial effects:

[0025] 1. The present application first comprehensively treats titanium dioxide waste acid and electroplating nickel recovery liquid, and the sulfuric acid obtained by treating the titanium dioxide waste acid is used as a raw material for treating the electroplating nickel recovery liquid, which not only saves resources but also realizes waste utilization, reduces the treatment pressure of the titanium dioxide plant waste acid, and achieves good economic and environmental benefits.

[0026] 2. The polymer-coated membrane electrodialysis system is used to treat the electroplating nickel recovery liquid, and the organic impurities and a small amount of inorganic impurities in the electroplating nickel recovery liquid are removed, and the product has high purity. A large amount of chemicals in the chemical precipitation method and the chemical oxidation method is not used, and additional pollution is not caused. The adsorption carrier in the activated carbon adsorption method also does not need to be treated. In addition, compared with ordinary electrodialysis, this method avoids the penetration of part of the positively charged organic substances into the nickel sulfate product through the cation exchange membrane, which affects the electroplating effect. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is a process flow chart of the method for comprehensive treatment of titanium dioxide waste acid and electroplating nickel recovery liquid according to Embodiment 1 of the present application;

[0028] Figure 2 is a di-valent cation separation membrane electrodialysis system of the method for comprehensive treatment of titanium dioxide waste acid and electroplating nickel recovery liquid according to Embodiment 1 of the present application;

[0029] Figure 3 is a polymer-coated membrane electrodialysis system of the method for comprehensive treatment of titanium dioxide waste acid and electroplating nickel recovery liquid according to Embodiment 1 of the present application. DETAILED DESCRIPTION

[0030] The technical solutions of the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0031] In the prior art, titanium dioxide waste acid and electroplating nickel recovery liquid are separately treated and irrelevant to each other, and the full utilization of waste resources cannot be achieved. The present application provides a method for comprehensive treatment of titanium dioxide waste acid and electroplating nickel recovery liquid, which comprises the following steps:

[0032] S1. treating titanium dioxide waste acid to separate sulfuric acid;

[0033] S2. treating electroplating nickel recovery liquid to separate nickel salt;

[0034] S3. reacting the sulfuric acid obtained in step S1 with the nickel salt obtained in step S2 to obtain nickel sulfate.

[0035] The method for comprehensive treatment of titanium dioxide waste acid and electroplating nickel recovery liquid has a flow chart as shown in Figure 1 The titanium dioxide waste acid refers to the waste acid generated in the production of sulfuric acid titanium dioxide, which contains a large amount of sulfuric acid and ferrous sulfate. In step S1 of the present application, sulfuric acid is separated from the waste acid by treating the titanium dioxide waste acid.

[0036] The electroplating nickel wastewater is a large amount of electroplating nickel wastewater generated by rinsing the plated parts or products in the electroplating process, and contains a large amount of heavy metal nickel, organic matter and a small part of inorganic impurities. The organic matter is mainly derived from various organic additives used in the electroplating process. The concentration of nickel in the electroplating nickel recovery liquid obtained by preliminary treatment of the electroplating nickel wastewater is low, and still contains a large amount of organic matter and part of inorganic impurities. In step S2 of the present application, the nickel salt is deeply separated from the recovery liquid by treating the electroplating nickel recovery liquid. The sulfuric acid separated in step S1 is used as a raw material for producing nickel sulfate, and reacts with the nickel separated in step S2 to obtain a relatively pure nickel sulfate solution. The present application realizes mutual utilization of waste resources, reduces waste and environmental pollution, can effectively reduce the environmental protection pressure of titanium dioxide production enterprises, and saves a large amount of raw material funds.

[0037] Preferably, the nickel sulfate obtained in step S3 is crystallized to obtain nickel sulfate crystals. The nickel sulfate crystals can be used as an electroplating solution in the electroplating nickel process for reutilization, saving raw material funds.

[0038] Preferably, in step S1, a monovalent and divalent cation separation membrane electrodialysis system is used; the monovalent and divalent cation separation membrane electrodialysis system comprises: a first anode plate, a first anion exchange membrane, a monovalent and divalent cation separation membrane, and a first cathode plate; the first anion exchange membrane and the monovalent and divalent cation separation membrane are each provided in at least one group, and the first anion exchange membrane and the monovalent and divalent cation separation membrane are alternately arranged between the first anode plate and the first cathode plate; a first feed chamber is formed between the first anion exchange membrane and the monovalent and divalent cation separation membrane, and the titanium dioxide waste acid is introduced into the first feed chamber for treatment.

[0039] As shown in Figure 2 from the first cathode plate to the first anode plate, respectively, comprising: a cathode electrode liquid chamber - a first feed chamber - an acid chamber - … - a first feed chamber - an acid chamber - a first feed chamber - an anode electrode liquid chamber, and the virtual frame is a plurality of repeating units. The monovalent and divalent cation separation membrane only allows monovalent cations to pass through, and the first anion exchange membrane only allows anions to pass through. The titanium dioxide waste acid solution containing ferrous sulfate and sulfuric acid enters the first feed chamber, and under the driving of an electric field, H + passes through the monovalent and divalent cation separation membrane into the acid chamber, and Fe 2+ cannot pass through the monovalent and divalent cation separation membrane and the first anion exchange membrane and remains in the first feed chamber. Part of SO4 2- passes through the first anion exchange membrane into the acid chamber, thereby separating ferrous sulfate and sulfuric acid. The plurality of repeating units can improve the separation efficiency of the monovalent and divalent cation separation membrane. The use of such an electrodialysis system has the advantages of low energy consumption and no environmental pollution.

[0040] The separation of ferrous sulfate and sulfuric acid in the titanium dioxide waste acid can also be realized by high-temperature concentration method, vacuum concentration method, membrane fractional filtration method, etc.

[0041] Preferably, the mono-divalent cation separation membrane is a polyethyleneimine modified membrane. Further preferably, the mono-divalent cation separation membrane is a polyethyleneimine (PEI) modified 324 (Dupont de Nemours). The separation between cations is based on the selectivity of the cation exchange membrane to monovalent ions. While PEI increases the positive charge on the membrane surface, it allows the retention of multivalent ions and the passage of monovalent ions, thus the introduction of polyethyleneimine (PEI) can improve the selectivity of the separation membrane.

[0042] When the mono-divalent cation separation membrane electrodialysis system is in operation, the current density is related to the membrane and the solution. The limiting current density is different for different equipment and different solutions. If the current density is too high, the membrane will be contaminated too quickly. If the current density is too low, the efficiency will be lower. Taking the above factors into consideration, preferably, the current density is 6-50 mA / cm 2 . Further preferably, the current density is 6-20 mA / cm 2 . Most preferably, the current density is 8 mA / cm 2 .

[0043] Preferably, in step S2, a polymer-coated membrane electrodialysis system is used; step S3 is specifically using the sulfuric acid obtained in step S1 as the stripping solution of the polymer-coated membrane electrodialysis system; the polymer-coated membrane electrodialysis system comprises a second anode plate, a second anion exchange membrane, a polymer-coated membrane, a third anion exchange membrane, a cation exchange membrane, and a second cathode plate; wherein the second anion exchange membrane, the polymer-coated membrane, the third anion exchange membrane, and the cation exchange membrane are sequentially arranged to form a repeating unit, and at least one set of repeating units is arranged between the second anode plate and the second cathode plate; the second anion exchange membrane and the polymer-coated membrane form a second feed chamber; the third anion exchange membrane and the cation exchange membrane form an acid inlet chamber, the electroplating nickel recovery liquid is fed into the second feed chamber for treatment, and the sulfuric acid obtained in step S1 is fed into the acid inlet chamber as the stripping solution.

[0044] As shown in Figure 3 , from the second anode plate to the second cathode plate, there are anode electrode liquid chamber-second feed chamber-stripping chamber-acid inlet chamber-acid production chamber…-cathode electrode liquid chamber, and the virtual frame is a plurality of repeating units. The polymer-coated membrane only allows Ni 2+ to pass through, the second anion exchange membrane and the third anion exchange membrane allow anions to pass through, and the cation exchange membrane allows cations to pass through. The electroplating nickel recovery liquid to be treated enters the second feed chamber, and contains a large amount of organic matter and part of inorganic impurities such as nickel chloride. Under the driving of the electric field, Ni 2+ passes through the polymer-coated membrane into the stripping chamber, SO4 2- and Cl -The organic matter cannot pass through the polymer coated membrane and the second anion exchange membrane and stays in the second feed chamber. The sulfuric acid separated from the titanium white waste acid is used as a stripping solution to enter the stripping chamber and react with the separated Ni 2+ to generate nickel sulfate; the other part enters the acid feed chamber, SO4 2- , and H 2- to generate mixed acid. The Ni + passes through the third anion exchange membrane into the stripping chamber to further supplement the SO4 2- concentration in the stripping chamber, H - , and Cl 2+ to generate mixed acid in the acid generation chamber. After the treatment by the polymer coated membrane electrodialysis system, the Ni 2 is separated from the nickel recovery liquid containing organic matter and part of inorganic impurities. The generated sulfuric acid and hydrochloric acid mixed acid can be used for pH adjustment in the electroplating process, and the liquid containing organic matter is discharged after biochemical treatment.

[0045] Preferably, the polymer coated membrane comprises a base polymer and a carrier; the base polymer is one or a combination of polyvinylidene fluoride resin or modified resin thereof, polyvinyl chloride resin or modified resin thereof, cellulose triacetate resin or modified resin thereof, and polytetrafluoroethylene resin or modified resin thereof; and the carrier is an extractant or an ionic liquid. The carrier is uniformly dispersed between the entangled chains of the base polymer, providing excellent stability to the polymer coated membrane. The transmission efficiency of metal ions in the polymer coated membrane is improved by applying an electric field as a driving force through electrodialysis.

[0046] Preferably, the carrier is an extractant. Preferably, the extractant is a tung oil-based extractant. Further preferably, the tung oil-based extractant is a synergistic solvent extraction (SSX) system composed of tung oil-based carboxylic acid (TFCA) and isonicotinate (4PC). This carrier takes into account the number of functional groups and the overall carbon chain structure, uses an unsaturated phthalate methyl ester long chain structure as a framework, and introduces a pair of chelating carboxyl groups on the conjugated olefin to improve the selectivity of the carboxylic acid extractant to divalent metal cations. It can chelate, complex or ion exchange with nickel, has high selectivity and good stability to nickel, thereby deeply separating nickel ions from the nickel recovery liquid containing organic matter and part of inorganic impurities, and further obtaining a relatively pure nickel salt solution.

[0047] Preferably, the current density is too small and the ion migration rate is too low when the polymer coated membrane electrodialysis system is treated, and the current density is too large and the energy consumption is too high. Considering the above factors, the current density is preferably 10-40 mA / cm 2 . Further preferably, the current density is 20-30 mA / cm 2 .

[0048] Preferably, in step S3, the concentration of sulfuric acid is 0.1-0.5 mol / L. Further preferably, the concentration of sulfuric acid is 0.2-0.3 mol / L, and most preferably, the concentration of sulfuric acid is 0.2 mol / L.

[0049] Preferably, in step S4, the preparation of the nickel sulfate crystal can adopt a crystallization method, a chemical precipitation method + acid leaching method, or an extraction method. Further preferably, the crystallization method is used to prepare the nickel sulfate crystal.

[0050] Example 1

[0051] The method for comprehensive treatment of titanium dioxide waste acid and electroplating nickel recovery liquid in this embodiment comprises the following steps:

[0052] (1) The titanium dioxide waste acid is treated by using a monovalent and divalent cation separation membrane electrodialysis system. The composition of the titanium dioxide waste acid is: sulfuric acid 4.5%, ferrous sulfate 1.9%.

[0053] The monovalent and divalent cation separation membrane electrodialysis system comprises, in sequence: an anode plate, a cation exchange membrane, a monovalent and divalent cation separation membrane, a cation exchange membrane, a monovalent and divalent cation separation membrane, and a cathode plate. The cation exchange membrane and the monovalent and divalent cation separation membrane form a feed chamber, the titanium dioxide waste acid is introduced into the feed chamber for treatment, the cation exchange membrane is an AMX (Tokuyama Corp.) membrane, and the monovalent and divalent cation separation membrane is a polyethyleneimine (PEI) modified 324 (Dupont de Nemours).

[0054] The titanium dioxide waste acid is introduced into the feed chamber of the monovalent and divalent cation separation membrane electrodialysis system, and after circulating for 10 min, a constant current is applied, and the current density is 8 mA / cm 2 The sulfuric acid concentration is monitored by sampling from the acid chamber every 2 h, and the specific results are shown in Table 1. Until the sulfuric acid concentration reaches 0.4 mol / L, i.e., 39.2 g / L, the monovalent and divalent cation electrodialysis system is turned off, and the prepared sulfuric acid solution is reserved.

[0055] Table 1

[0056] Run time (h) 2 4 6 8 10 Acid room sulphuric acid concentration (g / L) 10.34 19.31 28.28 34.48 40

[0057] (2) The electroplating nickel recovery liquid is treated by using a polymer-coated membrane electrodialysis system. The composition of the nickel-containing recovery liquid is shown in Table 2:

[0058] Table 2

[0059] Item Ni 2+ Concentration, g / L COD, mg / L pH Nickel containing recovery solution 2.52 2895.44 6.72

[0060] The polymer-coated membrane electrodialysis system comprises, in sequence, an anode plate, a negative ion exchange membrane, a polymer-coated membrane, a negative ion exchange membrane, a positive ion exchange membrane, a negative ion exchange membrane, a polymer-coated membrane, a negative ion exchange membrane, a positive ion exchange membrane, and a cathode plate, and a feed chamber is formed between the negative ion exchange membrane and the polymer-coated membrane; an acid chamber is formed between the negative ion exchange membrane and the positive ion exchange membrane. Both the negative ion exchange membrane and the positive ion exchange membrane are commercial ion exchange membrane products on the market. The polymer-coated membrane is prepared by a solvent evaporation casting method using a synergistic solvent extraction (SSX) system composed of tung oil-based carboxylic acid (TFCA) and isonicotinate (4PC) at a molar concentration ratio of 1:2 as a carrier and a polyvinylidene fluoride modified resin as a base polymer, and the ratio of the carrier to the base polymer is 2:3.

[0061] The nickel electroplating recovery liquid is introduced into the feed chamber of the polymer-coated membrane electrodialysis system, and the sulfuric acid obtained in the previous step is diluted to 0.2 mol / L and introduced into the stripping chamber and the acid chamber. Pure water is used in the acid production chamber, and a small amount of sulfuric acid solution is added at the beginning to avoid excessive resistance. After circulating the chambers for 10 minutes, a constant current is applied, and the current density is 30 mA / cm 2 . The Ni 2+ concentration is monitored every 2 h from the stripping chamber, and the specific results are shown in Table 3, until the Ni 2+ concentration reaches 10 g / L, and the polymer-coated membrane electrodialysis system is turned off.

[0062] Table 3

[0063] Run time (h) 2 4 6 8 10 Stripper Ni 2+ Concentration (g / L) 2.3 5.6 7.8 9.5 10.6

[0064] (3) The stripping liquid is added to a vacuum reaction kettle, vacuum concentrated, and when the density reaches 1.75 kg / L, it can be put into a centrifuge for dehydration to obtain green nickel sulfate crystals.

[0065] Example 2

[0066] The method for comprehensive treatment of titanium dioxide waste acid and nickel-containing recovery liquid in this example differs from that of Example 1 in that in step (1), the negative ion exchange membrane and the di-valent cation separation membrane are arranged in one group, i.e., the di-valent cation separation membrane electrodialysis system comprises, in sequence, an anode plate, a negative ion exchange membrane, a di-valent cation separation membrane, and a cathode plate. The sulfuric acid concentration in the acid chamber is shown in Table 4:

[0067] Table 4

[0068] Run time (h) 4 8 12 16 20 21 Acid room sulphuric acid concentration (%) 9.1 16.52 21.94 27.73 37.56 39.95

[0069] Example 3

[0070] The method for comprehensive treatment of titanium dioxide waste acid and nickel-containing recovery solution in this embodiment is different from that in embodiment 1 in that, in step (2), the repeating units of the anion exchange membrane, the polymer coating membrane, the anion exchange membrane, and the cation exchange membrane are arranged in one group, i.e., the polymer coating membrane electrodialysis system comprises, in sequence, an anode plate, an anion exchange membrane, a polymer coating membrane, an anion exchange membrane, a cation exchange membrane, and a cathode plate. The stripping chamber Ni 2+ The concentration change is shown in Table 5:

[0071] Table 5

[0072] Run time (h) 2 5 10 13 15 Stripper Ni 2+ Concentration (g / L) 1.1 2.3 6.2 8.9 11.3

[0073] Example 4

[0074] The method for comprehensive treatment of titanium dioxide waste acid and nickel-containing recovery solution in this embodiment is different from that in embodiment 1 in that, in step (2), the base polymer of the polymer coating membrane is a polyethylene modified resin.

[0075] Comparative Example

[0076] In the comparative example, the titanium dioxide waste acid and the nickel-containing recovery solution are treated separately. Specifically, the treatment of the titanium dioxide waste acid in step (1) is the same as in embodiment 1, the treatment of the nickel-containing recovery solution in step (2) is performed by using a common electrodialysis method, and the sulfuric acid separated in step (1) is not used in the reaction to generate nickel sulfate, and step (3) is the same as in embodiment 1.

[0077] The test data of the obtained nickel sulfate crystals in embodiment 1 to embodiment 4 and the comparative example are shown in Table 6:

[0078] Table 6

[0079]

[0080]

[0081] As can be seen from the data in Table 1 and Table 4, when the number of repeating units composed of the first anion exchange membrane and the di-valent cation separation membrane is increased, the time for the sulfuric acid concentration in the acid chamber to reach the target value is shortened from 21 hours to 10 hours, and the separation efficiency of the di-valent cation separation membrane electrodialysis system can be obviously improved.

[0082] As can be seen from the data in Table 3 and Table 5, when the number of repeating units composed of the second anion exchange membrane, the polymer coating membrane, the third anion exchange membrane, and the cation exchange membrane is increased, the time for the concentration of Ni 2+ in the stripping chamber to reach the target value is shortened from 15 hours to 10 hours, and the separation efficiency of the polymer separation membrane electrodialysis system can be obviously improved.

[0083] Compared with the comparative examples, the titanium white waste acid and the nickel-containing recovery solution are comprehensively treated in the examples 1-3, which can reduce environmental pollution and save a large amount of raw material funds.

[0084] As shown in the data in Table 6, the purity of the nickel sulfate crystals obtained in the examples 1-3 meets the national first-class standard and reaches the standard for recycling of the electroplating solution in the electroplating process, while the purity of the nickel sulfate crystals obtained in the comparative examples cannot meet the national first-class standard due to the failure to effectively and completely separate the organic matter from the nickel sulfate, and the obtained nickel sulfate crystals cannot be used for recycling of the electroplating solution.

[0085] Obviously, the above examples are merely examples for clear illustration, but not limitation on the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. All the embodiments do not need to be exhausted here. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A method for comprehensive treatment of titanium dioxide waste acid and electroplating nickel recovery solution, characterized in that, It comprises the following steps: S1. treating titanium dioxide waste acid to separate sulfuric acid; S2. treating electroplating nickel recovery liquid to separate nickel salt; S3. reacting the sulfuric acid obtained in step S1 with the nickel salt obtained in step S2 to obtain nickel sulfate; In step S1, a monovalent and divalent cation separation membrane electrodialysis system is used to complete the separation; the monovalent and divalent cation separation membrane electrodialysis system comprises a first anode plate, a first anion exchange membrane, a monovalent and divalent cation separation membrane, and a first cathode plate; the first anion exchange membrane and the monovalent and divalent cation separation membrane are each provided in at least one group, and the first anion exchange membrane and the monovalent and divalent cation separation membrane are alternately arranged between the first anode plate and the first cathode plate; a first feed chamber is formed between the first anion exchange membrane and the monovalent and divalent cation separation membrane, and the titanium dioxide waste acid is introduced into the first feed chamber for treatment; In step S2, a polymer-coated membrane electrodialysis system is used to complete the separation; and in step S3, the sulfuric acid obtained in step S1 is used as a stripping liquid for the polymer-coated membrane electrodialysis system; The polymer-coated membrane electrodialysis system comprises a second anode plate, a second anion exchange membrane, a polymer-coated membrane, a third anion exchange membrane, a cation exchange membrane, and a second cathode plate; wherein the second anion exchange membrane, the polymer-coated membrane, the third anion exchange membrane, and the cation exchange membrane are sequentially arranged to form a repeating unit, and at least one group of the repeating unit is arranged between the second anode plate and the second cathode plate; A second feed chamber is formed between the second anion exchange membrane and the polymer-coated membrane; a feed acid chamber is formed between the third anion exchange membrane and the cation exchange membrane, and the electroplating nickel recovery liquid is introduced into the second feed chamber for treatment, and the sulfuric acid obtained in step S1 is introduced into the feed acid chamber as a stripping liquid.

2. The method for comprehensive treatment of titanium dioxide waste acid and electroplating nickel recovery solution according to claim 1, characterized in that, The nickel sulfate obtained in step S3 is crystallized to obtain nickel sulfate crystals.

3. The method for comprehensive treatment of titanium dioxide waste acid and electroplating nickel recovery solution according to claim 1, characterized in that, The monovalent and divalent cation separation membrane is a polyethyleneimine modified membrane.

4. The method for comprehensive treatment of titanium dioxide waste acid and electroplating nickel recovery solution according to claim 3, characterized in that, The electric current density is 6-50 mA / cm2 when the di-valent cation separation membrane electrodialysis system is treated. 2 .

5. The method for comprehensive treatment of titanium dioxide waste acid and electroplating nickel recovery solution according to claim 1, characterized in that, The polymer-coated membrane comprises a base polymer and a carrier; The base polymer is one or a combination of polyvinylidene fluoride resin or modified resin thereof, polyvinyl chloride resin or modified resin thereof, cellulose triacetate resin or modified resin thereof, and polytetrafluoroethylene resin or modified resin thereof; The carrier is an extractant.

6. The method for comprehensive treatment of titanium dioxide waste acid and electroplating nickel recovery solution according to claim 5, characterized in that, The extractant is a tung oil-based extractant.

7. The method for comprehensive treatment of titanium dioxide waste acid and electroplating nickel recovery solution according to claim 5, characterized in that, The current density of the polymer coating film electrodialysis system during processing is 10-40 mA / cm 2 .

8. The method for comprehensive treatment of titanium dioxide waste acid and electroplating nickel recovery solution according to claim 5, characterized in that, In step S3, the concentration of the sulfuric acid is 0.1-0.5 mol / L.

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