JP2000345357A - Method for treating aged electroless nickel plating solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a treatment method capable of efficiently separating and removing Ni ions, a phosphite component and organic acids by a simple operation from an aged electroless Ni plating solution. SOLUTION: This treatment method comprises a process 1 in which Ni ions in an aged solution are separated and recovered as Ni metal through an electroless plating reaction caused by bringing an aged electroless Ni plating solution into contact with Ni powder, a process 2 in which the separated host solution in the process 1 is brought into contact with a chelate resin to absorb and separate residual Ni ions, a process 3 in which a dissolved phosphite component is separated and recovered as Ca phosphite by reacting gypsum or mineral acid and hydrated lime with the separated solution in the process 2, a process 4 in which the residual phosphite component is oxidized and decomposed in the presence of an oxidant into a phosphoric acid component and separated and recovered as Ca phosphate by a reaction with a Ca salt, and a process 5 in which organic substances in the separated solution in the process 4 are removed by an activated sludge process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for industrially efficiently dissolving and removing nickel ions, hypophosphorous acid, phosphorous acid and organic substances remaining in an aging solution for electroless nickel plating. The present invention relates to a method for treating an electroless nickel plating aging solution that is made pollution-free to a state.

[0002]

2. Description of the Related Art At present, electroless plating technology is utilized in various fields from decorative plating articles to production of functional electronic components such as magnetic disks and magnetic tapes. Nickel-cobalt alloys are partially applied in addition to nickel, which has been widely used in the past.

[0003] The electroless plating method is generally carried out by immersing a substrate to be plated in a plating solution prepared in advance and reacting it for an empirically determined time. Even with proper management, an increase in oxidation products during the reaction is inevitable, and the processing liquid used to some extent can no longer be reused.

For this reason, a bath solution that has undergone a certain plating reaction is
Despite large amounts of plating metal ions such as nickel ions and reducing components such as sodium hypophosphite remaining in the solution, they have often been discarded as plating aging solutions by means such as dumping into the ocean. .

[0005] However, marine dumping has been banned from the demands of pollution prevention and environmental purification, and on the other hand, from the viewpoint of active collection and reuse of valuable metal components contained, techniques for treating plating aging solutions have been actively developed. Some of them have been put to practical use.

[0006] As a method of treating the nickel plating aging solution,
Mainly the method of separating and recovering nickel ions, for example, a method of extracting and recovering nickel by electrolytic method, a method of injecting a large amount of iron powder or vanadium salt into a plating aging solution to induce self-decomposition and separating and recovering. A method in which an aluminum plate or an aluminum foil is put into an alkaline plating aging solution to precipitate nickel, then recovered with nitric acid, and nickel remaining in the mother liquor is adsorbed by a chelate resin (Japanese Patent Application Laid-Open No. S51-6136). Publication), a method of applying a plating aging solution to a raw material in a method of producing a powdered electroless plating powder by an addition method, and the like have been proposed.

Also, a method of separating and recovering dissolved phosphorous acid from the standpoint of environmental pollution has been proposed. For example, titanium oxide carrying a noble metal such as Pt while a plating aging solution is kept in an acidic state. Is used as a photocatalyst to oxidize hypophosphite ions to phosphate ions or calcium phosphate (JP-A-6-136549).

On the other hand, an active treatment method has been proposed in which nickel is separated and recovered from the plating aging solution, and further, phosphorous acid is recovered. For example, the plating aging solution and the mica powder are brought into contact with each other to perform electroless plating to recover nickel, and the mother liquor is oxidized with hydrogen peroxide or the like to be converted into orthophosphate ions.
²⁺ ) to precipitate and separate as calcium phosphite or calcium phosphate ("Study on Technology for Treatment of Phosphorus-Resistant Plating Waste Solution", Research Report of Product Chemistry, No. 121). A method of separating and recovering valuable resources without discharging pollution by removing the precipitates by treating with an acid, and then adding a mineral acid and a calcium compound and calcining the mixture in air (Japanese Patent Application Laid-Open No.
-206447) and the like. However, all of the above methods have operational or economic disadvantages and are difficult to implement industrially.

[0009]

SUMMARY OF THE INVENTION In view of the above problems, the present inventors have conducted intensive studies on a rational treatment method for an electroless nickel plating aging solution. And then subjecting it to an electroless plating reaction, nickel ions can be substantially completely and easily separated and recovered as nickel metal, and the phosphorous acid remaining in the separated mother liquor can be separated from gypsum or mineral acid and slaked lime. Have been found to be non-polluting to a state in which the plating aging solution can be discarded by separating and recovering it as calcium phosphite or calcium phosphate by an oxidation reaction. (Japanese Unexamined Patent Publication No. 9-176
No. 861) The present invention is a further improvement of the above invention,
By treating the separated mother liquor after contacting the electroless nickel plating aging solution with the nickel powder, with a chelate resin,
The inventors have found that nickel ions can be almost completely removed, and completed the present invention.

Further, the present inventors have found that the method for treating an electroless nickel plating aging solution of the present invention can efficiently separate and remove phosphorous acid components and organic substances in addition to nickel ions from the plating aging solution. Completed the invention.

[0011]

That is, according to the present invention, an electroless nickel plating aging solution is brought into contact with nickel powder to cause an electroless plating reaction to separate nickel ions in the aging solution as nickel metal. A treatment of an electroless nickel plating aging solution, comprising: a first separation step of recovering, and a second separation step of bringing the separated mother liquor of the first separation step into contact with a chelating resin and adsorbing and separating remaining nickel ions. About the method.

The second separation step relates to a method for treating an electroless nickel plating aging solution which is treated in a pH range of 6 to 9. Further, the present invention relates to a method for treating an electroless nickel plating aging solution, wherein the chelating resin used in the second separation step is H-type or H-type substituted chelating resin. The present invention relates to a method for treating an electroless nickel plating aging solution in which hypophosphorous acid dissolved by contact between the aging solution and nickel powder in the electroless plating reaction in the first separation step becomes phosphorous acid.

Further, the aging solution for electroless nickel plating has a third separation step of allowing gypsum or mineral acid and slaked lime to act on the separated liquid after the second separation step to separate and recover dissolved phosphorous acid as calcium phosphite. Regarding the processing method.

Further, an oxidizing agent is added to the separated liquid after the third separation step to oxidatively decompose the remaining phosphorous acid into phosphoric acid, and then a calcium salt is applied to separate and recover as calcium phosphate. The present invention relates to a method for treating an electroless nickel plating aging solution having four separation steps.

Further, the present invention relates to a method for treating an electroless nickel plating aging solution having a fifth separation step of removing organic substances in the separated liquid after the fourth separation step by an activated sludge method.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The electroless nickel plating aging solution to be treated according to the present invention is a nickel plating aging solution mainly using sodium hypophosphite as a reducing agent, but a plating waste solution using a nickel-cobalt alloy as a plating metal source. It can also be applied. The term "plating aging solution" as used here means that when electroless nickel plating is performed with a plating solution in a bath, sodium hypophosphite used as a reducing agent is oxidized, and the plating function gradually decreases with the generation of sodium phosphite. In addition, it refers to a bath solution for waste leaves that does not exhibit a replating function in a built bath even though a plating solution is newly collected and a considerable amount of Ni ²⁺ is contained.

Although the composition of the electroless nickel plating aging solution varies depending on the composition of the building bath and the plating conditions, an example of the composition of the nickel plating aging solution is, in most cases, 4 to 7 g / L of Ni ^2+. range of ^{_{H 2 PO 2 2- 25~55 g /}} L HPO 3 2- 80~l00 g / L SO 4 2- 30~75 g / L chelator ^{30~55 g / L Na + 46~120 g} / L The hydrogen ion concentration of the aging solution is usually pH 4.
It is about 5 to 5.5. However, the electroless nickel plating aging solution to be treated in the present invention is not limited to the above composition.

The first separation step according to the present invention is a step of selectively separating and recovering nickel ions as nickel metal from the aging solution for electroless nickel plating as described above. In other words, the purpose of this step is to complete the nickel plating reaction so as to substantially remove the dissolved nickel ions.

The aging solution for electroless nickel plating is usually an acidic solution having a pH of about 4.5 as described above. However, in the first step, the pH of the solution is adjusted to a range around neutrality, usually pH 6 in the treatment. To 9, preferably in the range of pH 7 to 8. For adjusting the pH, a commonly used alkaline agent such as sodium hydroxide or potassium hydroxide is used.

The feature of the first step in the present invention resides in that the electroless nickel plating aging solution adjusted to around neutrality is brought into contact with the nickel powder while stirring under heating to carry out the electroless plating reaction. Heating of the electroless nickel plating solution
Under operating conditions that are a requirement for efficiently recovering dissolved nickel ions, usually 50 to 90 ° C., preferably 60 to 90 ° C.
Maintain the temperature in the range of ８０80 ° C.

The nickel powder is a component that functions as a recovery agent for nickel ions, and can be used without any particular limitation as long as the metal nickel powder is not dispersed in water. The most preferable mode of operation is to repeatedly use the nickel powder used for the electroless reaction as it is. The reason for this is that the nickel powder used for the first electroless plating reaction can be repeatedly used, which is economically advantageous. If the nickel powder has grown in the course of the electroless plating reaction, it may be used after pulverization.

The operation of bringing the nickel powder non-contact into the above electroless nickel plating aging solution to react the electroless plating is as follows: (1) After introducing the nickel powder into the plating aging solution adjusted to pH 6 to 9 at room temperature, A method of performing an electroless plating reaction while stirring in a heated state of 50 to 90 ° C, (2) an aqueous slurry of nickel powder not yet adjusted to a temperature of 50 to 90 ° C and a pH of 6 to 9 (using a diluted aging solution as a dispersion medium) A method for simultaneously or continuously adding an electroless nickel plating aging solution and an alkali agent to the mixture, and performing an electroless plating reaction with stirring while maintaining the temperature and the pH as described above;
Alternatively, (3) any of these methods may be combined to cause an electroless plating reaction.

Of these, the method (1) is industrially most advantageous because the operation is simple and the nickel recovery rate is high. When the method (1) is used, the operation is not limited to one-stage operation, and can be performed continuously by performing multi-stage operation.

Since hydrogen gas is generated in the course of the electroless plating reaction, this gas bubble phenomenon serves as a measure of the start and end of the reaction. That is, the reaction end point is the point at which the gas foaming phenomenon stops. After completion of the electroless plating reaction, the treatment is completed by aging usually for 0.5 hour or more, preferably for 1 to 2 hours, followed by filtration and separation by a conventional method.

In the first separation step, nickel ions can be recovered as metallic nickel, and the recovered nickel component is used as valuable metal. Metallic nickel is recovered in the form of metal powder having an average particle size of about 0.1 to 50 μm.

However, in the first separation step,
When processing on an industrial scale, nickel ions remain in the mother liquor after separation. That is, in the second separation step, the separated mother liquor after the first separation step is brought into contact with the chelate resin to cause adsorption and separation of nickel ions.

The pH to be embedded may be the pH of the separated mother liquor after the first separation step, and is in the range of pH 6 to 9, preferably pH 7 to 8. In addition, it is preferable to use the mother liquor after filtering as necessary.

The contact condition between the separated mother liquor and the chelate resin after the first separation step is determined by the nickel ion concentration (mg /
L), mother liquor flow amount (L) and resin wet resin amount (LR)
Although the ratio varies depending on the ratio of liquid passing (L / LR), the value of the flowing speed SV and the total amount of Ni adsorbed on the chelating resin used, for example, the nickel ion concentration in the mother liquor is 265 mg / L.
In the case of L, the liquid passing speed SV = 1 and the liquid passing ratio (L / LR)
Sufficient adsorption is possible up to 60, preferably up to 50. In this case, the total amount of adsorption is 0.3 mol / L.

The flow rate (SV) is a value (L / hr) obtained by dividing the flow rate per unit time by the apparent volume of the ion exchange resin (chelate resin). Specifically, the liquid passing speed (SV) = X means that a liquid having a volume X times the apparent volume of the ion exchange resin (chelate resin) flows in one hour.
In the case of SV = 1, it indicates that liquid is passed through 1 liter (L) of the resin at 1 L / hr. The liquid passing speed (SV) is usually about 1 and is not particularly limited, but is preferably 0.5 to 5. In addition, the flow rate (L / LR) is not particularly limited.

The chelate resin to be used is not particularly limited as long as it can adsorb and recover nickel ions, and specific examples thereof include styrene-based such as Na-type, Ca-type and H-type, pyridine-based, and the like. A commercially available chelate resin for metal adsorption such as an acrylic resin is used. Preferably H
Type, or Na type or Ca type is replaced with H type.

Commercially available products include "Eporus" series (manufactured by Miyoshi Oil & Fats Co., Ltd.), "Sumiquilate" series and "Duolite" series (manufactured by Sumitomo Chemical Co., Ltd.),
A “Levacit” series (manufactured by Bayern Ltd.), a “Diaion” series (manufactured by Mitsubishi Chemical Corporation) may be used, but the present invention is not particularly limited thereto. The used resin can be regenerated by treating it with an acid such as sulfuric acid.

The hypophosphorous acid contained in the electroless nickel plating aging solution causes an electroless plating reaction by contacting the electroless nickel plating aging solution with nickel powder, and When the nickel ions are nickel metal, the hypophosphorous acid becomes phosphorous acid and is separated and recovered in the following third separation step.

Next, the third separation step of the present invention is a step of separating and recovering phosphorous acid from the mother liquor of the second separation step as phosphorous separated calcium. As a specific operation, gypsum or mineral acid and slaked lime are added to the mother liquor after the second separation step, and a reaction is performed under heating to precipitate and remove dissolved phosphorous acid as calcium phosphite.

In this third separation step, the concentration of phosphorous acid which can be applied is not particularly limited, but is usually 30% by weight.
Or less, preferably 20% by weight or less.

The gypsum and slaked lime used are not particularly limited, but are preferably finer particles from the viewpoint of reactivity. Specifically, the average particle diameter is usually 1 to 50 μm, preferably 10 to 50 μm, and particularly preferably about 10 to 50 μm. It is about 20 μm. This is because if the particle diameter exceeds 50 μm, the reactivity becomes poor, and if the particle diameter is less than 1 μm, it is difficult to obtain industrially.

The amounts of gypsum and slaked lime added are slightly smaller than the exact stoichiometry with respect to the amount of phosphorous acid contained in the mother liquor, and are usually 1.1 to 1.8 relative to phosphorous acid. The molar amount is twice as much, preferably 1.2 to 1.6 times.

The pH at the time of the reaction slightly varies depending on the kind of the calcium salt used. When gypsum is used, the pH of the reaction system is usually from 7 to 9, preferably around a neutral pH of 8. On the other hand, when slaked lime is used, the pH during the reaction
Is a weakly alkaline region of usually 7 to 12, preferably 8 to 10. The reaction system becomes strongly alkaline with the addition of the above amount of slaked lime in the reaction system. Therefore, the reaction proceeds by adding a mineral acid such as sulfuric acid or hydrochloric acid. In this case, the amount of the mineral acid to be added is at least equimolar to the amount of phosphorous acid contained in the mother liquor, preferably 1.0 to 1. It is 1-fold molar. The order of addition of the mineral acid and slaked lime does not have any particular problem, and they may be added at the same time or first.

The above reaction with gypsum or slaked lime usually has a temperature of 40 to 60 ° C, preferably 45 to 50 ° C.
The reaction time is not particularly limited as long as it is 0.5 hours or longer, but is usually 0.5 to 10 hours, preferably 1 to 3 hours. After completion of the reaction, the reaction mixture is separated by filtration in a conventional manner.

As can be seen from the above, the reaction between gypsum and the mother liquor is a typical metathesis reaction, and the reaction between slaked lime and the mother liquor is a metathesis reaction accompanied by neutralization. Depends on circumstances and economic reasons. The former reaction is greatly affected by the physical properties of the gypsum, and the reaction rate may be 90% or less. Therefore, when it is necessary to more completely remove phosphite ions, the latter reaction is advantageous.

The mother liquor treated in the third separation step contains substantially no nickel ions and has a phosphorous content of usually 8000 mg / L or less, preferably 5000 mg / L.
L or less.

Therefore, the mother liquor after the third separation step can be sufficiently discarded, but if stricter discharge regulations are required, the following fourth and fifth separation steps can be sequentially performed as desired. Then, phosphorous acid and organic substances are further removed from the mother liquor.

The fourth separation step is a step of oxidatively decomposing a phosphorous acid component into a phosphoric acid component and separating and recovering it as calcium phosphate. The specific operation method is to add an oxidizing agent to the mother liquor after the third separation step to oxidize and decompose phosphorous acid into phosphoric acid, and then add a calcium compound to separate and recover phosphoric acid as calcium phosphate I do.

The type of the oxidizing agent is not particularly limited, and a common oxidizing agent such as chlorine, sodium hypochlorite, hydrogen peroxide and ozone can be used. The addition amount of the oxidizing agent is usually 0.8 to 1.2 times mol, preferably 0.9 times mol, relative to the BOD amount. The reaction temperature is not particularly limited, and may be usually about 20 ° C. The pH of the reaction system is usually 1 to 5, preferably 2 to 3. The reaction time is not particularly limited as long as it is 1 hour or more, and is usually 1 to 4 hours, preferably 2 to 3 hours. By such an operation, the phosphorous acid component is oxidized to the orthophosphoric acid component.

Then, the remaining dissolved phosphoric acid component and a calcium salt are allowed to act to separate and recover calcium phosphate from the mother liquor, whereby oxyacid ions of phosphorus can be completely removed from the mother liquor. The amount of the calcium salt used is, for example, slaked lime, calcium chloride,
Gypsum etc., but calcium salt and pH of reaction system
Slaked lime, which also acts as a conditioning agent, is most advantageous.

The amount of the calcium salt to be added is not less than the stoichiometric amount, preferably about 1.5 to 2.0 times the molar amount of phosphoric acid. The reaction temperature is not limited, but is not lower than room temperature, preferably about 50 ° C. The pH of the reaction system is usually 7 to 10, preferably 8 to 9. The reaction time is not particularly limited because it is an instantaneous precipitation reaction, but it is usually 1 to 3 hours, preferably about 2 hours, in view of the aging operation in consideration of separability and the like. After completion of the reaction, the separated calcium is separated and recovered from the mother liquor by filtration by a conventional method.

The fifth separation step is a step of biologically removing organic substances remaining in the separated mother liquor after the fourth separation step by an activated sludge method. Activated sludge includes Ba, a common bacterium.
Cillus, Pseudomonas
(Pseudomonas) genus, Flavobacterium
(Flavobacterium) genus, Nitrobactor
(Nitrobactor) genus, Zooglea
The genus, Sphaerotilus genus, and the like can be used, but are not particularly limited thereto.

The total amount of activated sludge in the aeration tank (MLSS concentration)
Is usually 2000 to 3000 mg / L, preferably 250
0 mg / L, and the residence time of the treated water is not particularly limited as long as it is 40 hours or longer, and is usually 40 to 60 hours, preferably 50 hours.

According to the present invention, the first separation step, the second separation step, and the third separation step, the fourth separation step, and the fifth separation step are sequentially performed to obtain nickel in the electroless nickel plating aging solution. The ion concentration is usually 1 mg / L or less, preferably 0.5 mg / L or less, and the BOD concentration is usually 30 mg / L or less.
mg / L or less, preferably 15 mg / L or less, and the P concentration is usually 10 mg / L or less, preferably 4 mg / L or less. Can be processed.

[0049]

The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 A used electroless nickel plating aging solution having the composition shown in Table 1 was used.

[0051]

[Table 1]

First separation step Electroless nickel plating aging solution lt (specific gravity: 1.
2, pH 4.5) but not nickel powder (average particle size 3 μm) 1
0Kg was added, and 50 wt% NaOH was added dropwise while adding pH.
Was maintained at 8 and the temperature was raised until the reaction started. Hydrogen gas is generated at a temperature of about 65 ° C., and while maintaining the pH at 8 by dropwise addition of 50 wt% NaOH, the temperature is further raised to 80 ° C.
Heated for 1 hour. After the completion of the electroless plating reaction, the mixture was separated by filtration by a conventional method, and 13.9 kg of nickel metal (average particle size: 3.5 μm) was separated and recovered (removal rate: 94.7%). The mother liquor after filtration and separation contained 265 m of nickel ions.
g / L and 148 g / L of phosphorous acid remained.

Second separation step The mother liquor (pH 6.96) after the first separation step is
mmφ to EPORAS MX-2 (H type) (Miyoshi Oil & Fat Co., Ltd.)
(L) was passed through a resin tower containing 10 L at a liquid passing speed SV = 1. The flow rate (L / LR) was up to 65. Table 2 shows the results of the effluent nickel ion concentration and the pH.

[0054]

[Table 2]

(Regeneration of Chelate Resin) The chelate resin saturated above was regenerated under the following conditions. The results are shown in Table 3.

[0056]

[Table 3]

Example 2 First Separation Step Electroless nickel plating aging solution 1 having the same composition as in Example 1
10 kg of nickel powder (average particle size: 3 μm) was added to t (specific gravity: 1.2, pH: 4.5), the pH was maintained at 8 while 50 wt% NaOH was added dropwise, and the temperature was raised until the reaction started. Hydrogen gas is generated at a temperature of about 65 ° C., and 50 wt% N
While maintaining the pH at 8 by dropwise addition of aOH, a further 80
C., and aged for 1 hour. After the completion of the electroless plating reaction, filtration and separation were carried out by a conventional method, and 13.7 kg of nickel metal (average particle size: 3.3 μm) was separated and recovered (removal rate: 8)
9.0%). In the mother liquor after filtration and separation, 549 mg / L of nickel ions and 160 g / L of phosphorous acid remained.

Second separation step The mother liquor (pH 6.96) after the first separation step is
mmφ to EPORAS MX-2 (H type) (Miyoshi Oil & Fat Co., Ltd.)
(L) was passed through a resin tower containing 10 L of liquid at a liquid passing speed of SV = 1. The flow rate (L / LR) was up to 10. Table 4 shows the results of the outflow nickel ion concentration and pH.
Shown in

[0059]

[Table 4]

(Regeneration of Chelate Resin) The chelate resin used was regenerated under the following conditions. The results are shown in Table 5.

[0061]

[Table 5]

(Use after Regeneration) Table 6 shows the result of similarly reusing the regenerated chelate resin under the conditions in the second separation step.

[0063]

[Table 6]

From the above results, it was found that nickel ions could be treated by passing the chelate resin through, and the chelate resin could be regenerated with sulfuric acid. In addition, the regenerated resin was able to sufficiently process nickel ions.

Example 1 First separation step Electroless nickel plating aging solution 1 having the same composition as in Example 1
t (specific gravity 1.2, pH 4.5) nickel powder not 10kg
Was added, and the pH was maintained at 8 while adding 50 wt% NaOH dropwise, and the temperature was raised until the reaction started. Hydrogen gas is generated at a temperature of about 65 ° C., and 50 wt% NaOH is dropped to adjust the pH.
While keeping the temperature at 8, the temperature was further raised to 80 ° C., and the mixture was aged for 1 hour. After the completion of the electroless plating reaction, the mixture was separated by filtration by a conventional method, and 14.5 kg of nickel metal was separated and recovered (removal rate: 99.9%). In addition, the mother liquor after filtration and separation includes:
Nickel ion is 265mg / L, phosphorous acid content is 148g
/ L remained.

Second separation step The mother liquor (pH 6.96) after the first separation step is
mmφ to EPORAS MX-2 (H type) (Miyoshi Oil & Fat Co., Ltd.)
Was passed through a resin tower containing 20 L of liquid at a liquid passing speed SV = 1. The flow rate (L / LR) was adjusted to 50, the outflow nickel ion concentration was 0.3 mg / L, and the pH of the outflow liquid was 8.20.

Third Separation Step To the separated solution in the second separation step, 366 kg of 50 wt% sulfuric acid and 180 kg of slaked lime powder were added (pH 9). The temperature was raised to 50 ° C. and aged for 2 hours while stirring. Next, the reaction solution was separated by filtration in a usual manner, and 355 kg of calcium phosphite was separated and collected (removal rate: 95%). In addition,
6.6 g / L of phosphorous acid remained in the mother liquor after filtration and separation.

By the above two steps, nickel and phosphorus can be recovered from the plating aging solution as valuable resources, respectively.
As a result, it was found that the plating aging solution can be rationally processed.

Fourth separation step 1.35 t of mother liquor after the third separation step (BOD: 3500 m
g / L) with 16 kg of chlorine gas,
The phosphite content was oxidatively decomposed for minutes. Next, 12.5 Kg of slaked lime powder was added, and the mixture was heated at 50 ° C. for 2 hours with stirring. After completion of the reaction, the reaction mixture was separated by filtration in a conventional manner to recover 24 kg of calcium phosphate (removal rate: 99%). The mother liquor after the filtration separation had a phosphoric acid content of only 20 as PO ₄ ^3-.
It was only as low as mg / L.

Fifth Separation Step 1.345 t of the mother liquor after the fourth separation step was subjected to activated sludge treatment for 50 hours in an aeration tank (MLSS amount: 2500 mg / L) of 2 m ³ for 50 hours to remove organic substances, and 19 kg. Sludge cake was removed (BOD removal rate 99%). As a result,
As shown in Table 7, the main liquid composition of the final treated water was completely rendered harmless and could be discharged as it was.

[0071]

[Table 7]

(Note) The removal rate of P was calculated based on the hypophosphorous acid content before the treatment and the P content in the phosphorous acid content.

[0073]

As described above, according to the method for treating an electroless nickel plating aging solution of the present invention, nickel ions, phosphorous acid and organic substances can be industrially efficiently removed from the plating aging solution by a simple operation. It can be separated and removed well, and it can be made pollution-free until it can be disposed of, and its industrial utility value is extremely large.

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Claims (7)

[Claims] A first separation step of causing an electroless plating reaction to occur by contacting the electroless nickel plating aging solution with nickel powder, and separating and recovering nickel ions in the aging solution as nickel metal; A method for treating an electroless nickel plating aging solution, comprising a second separation step of bringing a separated mother liquor of one separation step into contact with a chelating resin and adsorbing and separating remaining nickel ions. 2. The method for treating an electroless nickel plating aging solution according to claim 1, wherein the second separation step is performed in a pH range of 6 to 9. 3. The chelating resin used in the second separation step is H-type or H-type substituted chelating resin.
Or the method for treating an electroless nickel plating aging solution according to 2 above. 4. The electroless nickel plating aging solution according to claim 1, wherein, in the electroless plating reaction in the first separation step, hypophosphorous acid dissolved by contact between the aging solution and the nickel powder becomes phosphorous acid. Processing method. 5. The method according to claim 1, further comprising a third separation step of causing gypsum or mineral acid and slaked lime to act on the separated liquid after the second separation step to separate and recover dissolved phosphorous acid as calcium phosphite. 4. The method for treating an electroless nickel plating aging solution according to any one of the above items 4. 6. An oxidizing agent is added to the separated liquid after the third separation step to oxidatively decompose the remaining phosphorous acid into a phosphoric acid, and then a calcium salt is actuated to separate and collect as calcium phosphate. The method for treating an electroless nickel plating aging solution according to any one of claims 1 to 5, further comprising a fourth separation step. 7. The electroless nickel plating aging solution according to claim 1, further comprising a fifth separation step of removing an organic substance in the separated liquid after the fourth separation step by an activated sludge method. Processing method.