JP3478947B2 - Regeneration method of ferric chloride solution - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferric chloride liquid for regenerating the ferric chloride liquid from an etching waste liquid after etching a metal to be etched using the ferric chloride liquid. Regarding how to play.

[0002]

2. Description of the Related Art Ferric chloride (FeCl ₃ ) liquid is used as an etching agent for printed boards and shadow masks. Among them, the etching of the shadow mask is to dissolve nickel and iron in the shadow mask made of a nickel (Ni) -iron (Fe) alloy by using a ferric chloride solution, and the following (1) and (2 ) It progresses according to the reaction formula shown in the formula. _{Fe + 2FeCl 3 → 3FeCl 2 ···} (1) Ni + 2FeCl 3 → 2FeCl 2 + NiCl 2 ··· (2)

Therefore, the etching solution (ferric chloride solution) after the etching treatment contains ferric chloride (FeCl ₂ ) and nickel chloride (NiCl) which are products of the etching reaction.
₂ ) is contained in the etching waste liquid (hereinafter referred to as waste liquid) in order to regenerate ferric chloride from ferrous chloride and precipitate nickel chloride to effectively utilize nickel. A method of regenerating the waste liquid by adding a reducing agent is adopted.

In this method, the waste liquid is the following (3) to (6)
It is processed through the steps shown in the formula. That is, the nickel chloride contained in the waste liquid is precipitated as nickel metal by reaction with iron to be recovered (equation (3)), the reaction between iron and ferric chloride (equation (4)), and iron and chloride. Reaction with nickel (equation (3)) and reaction between iron and hydrogen chloride (HCl) contained in the etching solution (equation (5)) produce ferrous chloride, which is chlorinated. By performing (Equation (6)), the etching solution is regenerated as ferric chloride solution.

[0005] _{Fe + NiCl 2 → Ni + FeCl} 2 ··· (3) Fe + 2FeCl 3 → 3FeCl 2 ··· (4) Fe + 2HCl → FeCl 2 + H 2 ··· (5) FeCl 2 + 1 / 2Cl 2 → FeCl 3 ··· ( 6)

However, in this regenerating method, as shown in the equation (4), 1.5 times as much ferric chloride as the ferric chloride in the waste liquid is produced, so that the amount of the etching liquid after the regenerating is It is about 1.5 times larger than that before playback. Here, the ferric chloride solution is used for etching,
It is also used as a coagulating sedimentation agent for water treatment of municipal sewage and industrial wastewater, but since the coagulation sedimentation agent is changing to an organic polymer type in recent years, there is little use of excess of regenerated ferric chloride solution. I have to throw it away after all. By the way, this waste is disposed as an industrial waste through a waste liquid treatment such as a neutralization treatment, which is troublesome and costly.

Therefore, as a method of regenerating the waste liquid without increasing the amount, the Japanese Examined Patent Publication No. 63-54795 and Japanese Patent Laid-Open No. 6-24 are available.
An electrolytic method is proposed in Japanese Patent No. 0475. Among them, the method of Japanese Examined Patent Publication No. 63-54795 discloses a method in which a waste liquid is electrolytically treated at a low current density in a cathode chamber of a first electrolytic cell partitioned by a diaphragm to electrolytically reduce metal ions in the waste liquid, and then this cathode is used. For the waste liquid in the chamber, electrolysis is performed with a low current density on the anode side and a high current density on the cathode side in the second electrolysis tank,
Part of the reduced metal ions is deposited and attached to the cathode, and then the waste liquid after the treatment is introduced into the anode chamber of the first electrolytic cell to oxidize the metal ions at a low current density.

Further, in the method disclosed in Japanese Patent Laid-Open No. 6-240475, an iron chloride-based etching solution containing nickel is treated by a diaphragm electrolysis method, and nickel and iron are electrolytically deposited at a cathode and recovered, and at the same time, in a cathode chamber. The generated chlorine gas is introduced into an etching solution containing ferrous chloride and the solution is oxidized.

[0009]

However, in the method of Japanese Patent Publication No. 63-54795, the first electrolytic cell,
Since two electrolysis cells called the second electrolysis cell are required and the metal is deposited at the cathode of the second electrolysis cell, it is necessary to adopt a structure for removing the deposited metal, including the electrolysis cell. There is a problem that the device structure becomes complicated. Also in the method disclosed in JP-A-6-240475, since the metal is deposited at the cathode, a structure for removing the deposited metal is required, and since chlorine gas generated at the anode is used, the chlorine A gas absorption tower is required, and there is also a problem that the device structure becomes complicated.

The present invention has been made under such circumstances, and an object thereof is to remove a second chloride from an etching waste liquid after etching a metal which is a material to be etched by using a ferric chloride solution. An object of the present invention is to provide a method for regenerating a ferric chloride solution capable of regenerating the ferric chloride solution while suppressing an increase in the amount of the solution by a simple method in regenerating the iron solution.

[0011]

Therefore, according to the present invention, the etching waste liquid containing the metal and ferric chloride after the metal forming the material to be etched is etched by using the ferric chloride liquid as the etching liquid. In the method for regenerating the ferric chloride liquid for regenerating the ferric chloride liquid from the etching waste liquid in the cathode chamber of the electrolytic cell divided into the cathode chamber and the anode chamber by the membrane that is substantially impermeable to water. Redox potential
Electrolyzing while detecting, in a state in which the ferric chloride slightly remains in the etching waste liquid so that the metal does not precipitate,
Until said oxidation reduction potential reaches the first potential, and a reducing step of reducing the bulk of the ferric chloride contained in the waste etching solution to ferrous chloride, followed by electrodeposition of the reduction step is performed
The etching waste liquid after dissolution is taken out of the cathode chamber, and a demetallizing step of separating the metal in this waste liquid, and then the etching waste liquid subjected to the demetallizing step is introduced into the anode chamber to reduce the redox potential. Electrolyzes while detecting , chlorine gas is emitted
The ferrous chloride is not contained in the etching waste liquid so that it does not grow.
The redox potential becomes the second potential while remaining
Up to the oxidation step of oxidizing ferrous chloride contained in the etching waste liquid to regenerate the ferric chloride solution, and performing the reducing step and the oxidizing step in the same electrolytic cell at the same time. Characterize.

Here, as the material to be etched,
Copper, nickel, chromium, nickel-iron alloys or iron-nickel-chromium alloys can be used. Or as a diaphragm which does not transmit pre Symbol substantially water was, for example, water permeability is 0.
It is preferable to use a diaphragm of 3 cc / cm 2 · min or less.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described. FIG. 1 is a configuration diagram showing an embodiment of a ferric chloride liquid regenerating apparatus for carrying out the method of the present invention. Reference numeral 1 in the figure denotes a waste liquid receiving tank for storing an etching waste liquid (hereinafter referred to as a waste liquid) described later, and a waste liquid circulating tank 2 is provided on the downstream side of the waste liquid receiving tank via a pipe T1 equipped with a pump P.

An electrolytic bath 3 is provided on the downstream side of the waste liquid circulating bath 2, and the electrolytic bath 3 is divided into a cathode chamber 31 and an anode chamber 32 by a diaphragm 33. The cathode chamber 31 and the anode chamber 32 are provided with a cathode 31a and an anode 32a, respectively. For example, both the cathode 31a and the anode 32a are composed of a titanium electrode coated with a noble metal such as a white metal. The cathode 31a and the anode 32a are connected to the cathode side and the anode side of the power supply unit 34, respectively.

The diaphragm 33 is made of a film that has a good electricity flow and is substantially impermeable to water.
As such a film, for example, a product name Yumicron film (manufactured by Yuasa Corporation) or the like can be used. This Yumicron film is made of polyvinyl chloride and has a thickness of 0.
22 mm, average pore diameter 0.05 μm, electric resistance 0.001
It is a neutral membrane with Ωdm ² and water permeability of 0.0008 cc / cm ² · min or less. This membrane has a low electrical resistance and therefore good electricity flow. It does not.

Circulation pipes T2 and T3 for circulating the waste liquid between the waste liquid circulation tank 2 and the cathode chamber 31 are provided between the waste liquid circulation tank 2 and the cathode chamber 31. The circulation pipe T
3 is equipped with a valve V3. The circulation pipe T3 is a pipe T4 provided with a valve V2 between the valve V1 and the cathode chamber 31.
This pipe T4 is connected to an apparatus (not shown) in the denickeling step (demetallizing step) which is the next step.

An anolyte circulation tank 5 is provided on the downstream side of the electrolytic bath 3 and the nickel removal step, and the anolyte circulation tank 5 is supplied with the waste liquid from which nickel has been removed in the nickel removal step. Is configured. Further, circulation pipes T5 and T6 for circulating the anolyte between the anode chamber 32 and the anolyte circulation bath 5 are provided between the anode chamber 32 and the anolyte circulation bath 5, and the circulation pipe T6. Is equipped with a valve V3. The circulation pipe T6 branches into a pipe T7 provided with a valve V4 between the anode chamber 32 and the valve V3, and this pipe T7 is connected to the ferric chloride liquid storage tank 6.

The waste liquid circulation tank 2 is provided with an oxidation-reduction potentiometer 41 for measuring the oxidation-reduction potential of the waste liquid in the tank and a liquid level gauge 42 for detecting the liquid level of the waste liquid in the tank. The opening and closing of the valves V1 and V2 are controlled based on these detected values. Further, the anolyte circulation tank 5 is also provided with an oxidation-reduction potentiometer 43 and a liquid level gauge 44, and the opening and closing of the valves V3 and V4 are controlled based on the detected values.

Next, the method for regenerating the ferric chloride solution of the present invention carried out in such an apparatus will be described with reference to the process diagrams shown in FIGS. 1 and 2. The waste liquid receiving tank 1 stores the etching waste liquid after etching the iron-nickel alloy that is the material to be etched with an etching liquid composed of ferric chloride liquid, for example. The waste liquid contains etching products such as FeCl ₂ and NiCl ₂ and unreacted FeC.
l ₃ and the content of each is, for example, FeCl
₂ 1.7%, Ni 0.7%, FeCl ₃ 46%.

First, the waste liquid in the waste liquid receiving tank 1 is supplied to the waste liquid circulating tank 2 through the pipe T1, the valve V2 is closed, and the valve V is closed.
1 is opened, and the waste liquid is circulated in the waste liquid circulation tank 2 and the electrolytic chamber 3 and the cathode chamber 3
It is circulated through the circulation pipes T2 and T3 with respect to 1. The anode chamber 32 of the electrolytic cell 3 is supplied with the liquid (ferrous chloride liquid) after the nickel removal process as described later, and the water pressure in the anode chamber 32 is slightly higher than that in the cathode chamber 31. The supply amount of each liquid to each chamber is controlled so as to be large.

When electrolysis is performed in the electrolytic cell 3 in this state, the unreacted FeCl ₃ contained in the waste liquid is reduced to FeCl ₂ in the cathode chamber 31 by the reaction represented by the following equation (7) (reduction step). . ^{_{FeCl 3 → FeCl 2 + Cl -}} ··· (7)

In the waste liquid circulation tank 2, the redox potential of the waste liquid in the tank is detected by the redox potential meter 41 at any time while the waste liquid is being circulated. It gradually becomes lower as you stay. In this way, for example, when the detected value of the waste liquid reaches the first potential of 450 mV, the valve V1 is closed and the valve V2 is opened, and the waste liquid is sent to the next process, the nickel removal process, through the pipe T4. . The composition of the waste liquid sent here is FeC.
1239%, Ni 0.7%, FeCl 33%.

In the waste liquid circulation tank 2, when the liquid level in the tank reaches the lower limit set value of the liquid level gauge 42, the valve V2 is closed and the valve V1 is opened to stop the liquid supply, and the waste liquid is received. The liquid is supplied from the tank 1 until the liquid level in the tank reaches the upper limit set value of the liquid level gauge 42, and is circulated again between the waste liquid circulation tank 2 and the cathode chamber 31.

Here, when the oxidation-reduction potential of the waste liquid reaches 450 mV, the electrolysis is terminated by F shown in FIG. 3 (a).
As is clear from the characteristic diagram showing the relationship between the eCl ₃ concentration and the redox potential, the FeCl ₃ concentration in the waste liquid becomes 3% or less when the redox potential becomes 450 mV or less, and most of the unreacted FeCl ₃ is FeCl _3. It is thought that it was reduced to ₂ .

[0025] Although thus remain slightly FeCl ₃ in waste, deposition of nickel on the cathode chamber 31 is suppressed by thus be left with FeCl _3. That is, in the cathode chamber 31, the reduction reaction to FeCl ₂ occurs preferentially over the nickel precipitation reaction, but if all the unreacted FeCl ₃ is reduced, the nickel precipitation reaction occurs.

In the nickel removal step, for example, nickel chloride contained in the waste liquid is reacted with iron to precipitate as nickel metal, and then solid-liquid separation is performed to recover the nickel metal. The waste liquid after nickel separation is sent to the anolyte circulation tank 5. The waste liquid (anolyte) contains, for example, FeCl 2.
₂ is 40%, FeCl ₃ is 0%, and Ni is contained at about 10 ppm. Here, FeCl ₃ is 0% because FeCl ₃ is reduced to FeCl ₂ by the reaction with iron.

Subsequently, the anolyte in the anolyte circulation tank 5 was closed by closing the valve V4 and opening the valve V3, and the anode chamber 32 of the electrolytic cell 3 was opened.
And circulation via the circulation pipes T5 and T6. Anode chamber 3
In 2, the FeCl ₂ contained in the anolyte solution is oxidized to FeCl ₃ by the reaction shown in the following equation (8) to regenerate the ferric chloride solution (oxidation step). FeCl ₂ + 1 / 2Cl ₂ → FeCl ₃ (8)

In the anolyte circulation tank 5, while the anolyte is being circulated, the redox potential of the anolyte in the tank is detected at any time by the redox potential meter 43. As you carry out, it will gradually become higher. Thus, for example, the detected value of the anolyte is the second potential, for example, 6
At 50 mV or higher, preferably 750 mV, the valve V3 is closed and the valve V4 is opened to feed the regenerated ferric chloride solution to the ferric chloride solution storage tank 6 through the pipe T4. The composition of the waste liquid stored in the ferric chloride liquid storage tank 6 is
FeCl350%, FeCl20.2%, Ni30pp
It is about m. The reason why the Ni concentration becomes slightly higher is that Ni slightly penetrates through the diaphragm 33 and enters the anode chamber 32 from the cathode chamber 31 as described later.

In the anode circulation tank 5, when the liquid level in the tank reaches the lower limit set value of the liquid level gauge 44, the valve V4 is closed to stop the liquid feeding, and the valve V3 is opened to remove the anolyte. It is supplied from the nickel process to the anolyte circulation tank 5 until the liquid level in the tank reaches the upper limit set value of the liquid level gauge 44, and is again circulated between the anolyte circulation tank 5 and the anode chamber 32. On the other hand, the ferric chloride solution in the ferric chloride solution storage tank 6 is used as an etching solution again after its concentration is adjusted.

Here, the redox potential of the anolyte is 650 mV.
It is preferable to terminate the electrolysis at 750 mV as described above, as is clear from the characteristic diagram showing the relationship between the FeCl ₂ concentration and the redox potential shown in FIG. 3B, when the redox potential is 650 mV or more. Then, the FeCl ₂ concentration in the waste liquid becomes 3% or less, and when it becomes 750 mV or more, the FeCl ₂ concentration becomes 0.2% or less, and most of FeCl ₂ is FeCl _2.
This is because it is thought that it was oxidized to ₃ .

Although FeCl ₂ slightly remains in the ferric chloride solution regenerated in this way, the generation of chlorine gas in the anode chamber 32 can be suppressed by allowing FeCl ₂ to remain. That is, in the anode chamber 32, the oxidation reaction to FeCl ₃ occurs preferentially over the generation reaction of chlorine gas.
This is because the chlorine gas generation reaction will occur if all of the eCl ₂ is reduced.

As described above, in the method of the present invention, the reduction reaction of FeCl ₃ → FeCl ₂ is performed in the cathode chamber 31, and the cathode chamber 3
In the anode chamber 32, an oxidation reaction of FeCl ₂ → FeCl ₃ is performed on the liquid obtained by removing nickel from the waste liquid discharged from No. 1 to regenerate ferric chloride. Therefore, (7) above
As is clear from the reaction formula shown in the formula (8), since ferrous chloride and ferric chloride are regenerated in a one-to-one relationship,
The ferric chloride liquid can be regenerated while suppressing the increase in the amount of the liquid. The Ni content of the regenerated ferric chloride solution is 30.
Since it is as low as about ppm, it can be used as an etching solution.

Further, in the electrolysis, since a special membrane having good electricity passage and substantially impermeable to water is used as the diaphragm 33, the electrolysis can be effectively advanced. That is, since the diaphragm 33 has an extremely small electric resistance and is good for passing electricity, Cl ⁻ generated by the reaction of the formula (7) in the cathode chamber 31 quickly permeates to the anode chamber through the diaphragm 33, and the anode chamber 32 In, the reaction of formula (8) proceeds.

On the other hand, the waste liquid in the cathode chamber 31 contains Ni ²⁺ and Fe.
^{Although 2+} and Fe ³⁺ are present, the water permeability of the diaphragm 33 is extremely low, and in the above-described embodiment, the water pressure in the anode chamber 32 is set higher than that in the cathode chamber 31, so that the cathode chamber 32 side is exposed. Three
Since water pressure is applied to the 1 side, they hardly permeate the diaphragm 33.

That is, Cl ⁻ , Ni ^2+, etc. ride on the liquid flow of the electrolytic solution (etching waste liquid) in the cathode chamber 31 and the anode chamber 3
However, if the water permeability of the diaphragm 33 is extremely low, the permeation amount of the electrolytic solution from the cathode chamber 31 to the anode chamber 32 is extremely small, so that cations such as Ni ^{2+ can} enter the anode chamber 32. The amount of transmission can be extremely reduced. At this time, if the water pressure is applied from the side of the anode chamber 32 to the side of the cathode chamber 31, the electrolytic solution in the cathode chamber 31 will further permeate into the anode chamber 32.
Since it is difficult to do BR>, it is possible to further suppress the permeation of cations such as Ni ²⁺ .

On the other hand, since Cl ^- is an anion,
Although the permeation of the electrolytic solution into the anode chamber 32 due to the liquid flow is almost suppressed, it moves to the anode chamber 32 by the electric force of the anode 32a, and as described above, the diaphragm 3
Since 3 has a good electricity flow, Cl ⁻ quickly permeates the diaphragm 33. If a diaphragm with a high electric resistance and poor electricity flow is used, it takes time to electrolyze,
It is considered that the throughput deteriorates and the amount of Ni ²⁺ entering the anode chamber 32 from the cathode chamber 31 increases.

As described above, in this embodiment, since the diaphragm 33 having a good electricity flow and a low water permeability is used, only Cl ⁻ can be selectively permeated into the anode chamber 32. If such a film is not used, since the waste liquid containing nickel is supplied to the cathode chamber 31 and the waste liquid from which nickel has been removed is supplied to the anode chamber 32 in the present invention, the cathode chamber 31 during the electrolysis. Therefore, Ni ²⁺ penetrates the diaphragm 33 and enters the anode chamber 32, and Ni enters the product.

If an anion exchange membrane is used as a diaphragm, only Cl ⁻ can be selectively moved to the anode chamber 32, but since ^ions such as Ni ²⁺ block the diaphragm, the electrolytic voltage becomes high. As a result, the useful life of the diaphragm is shortened, which is considered to be impractical.

Here, it is preferable that the water permeability of the diaphragm 33 is 0.3 cc / cm ² · min or less and the electric resistance is 0.013 Ωdm ² or less, according to an embodiment described later. If such a diaphragm 33 is used, the concentration of Ni that actually permeates the diaphragm 33 and enters the anode chamber 32 from the cathode chamber 31 is about 50 p.
It can be suppressed to about pm or less, and the ferric chloride solution usable as an etching solution can be regenerated. The water permeability of the diaphragm is determined by the average pore size of the membrane, the thickness of the membrane, and the like.

Further, in the method of the present invention, the oxidation-reduction potential of the waste liquid is detected, and the timing of the termination of electrolysis in the cathode chamber 31 and the timing of termination of the electrolysis in the anode chamber 32 are controlled by the method, so that the above-mentioned method is used. Thus, the nickel precipitation reaction in the cathode chamber 31 and the chlorine gas generation reaction in the anode chamber 32 can be suppressed.

Therefore, there is no need to remove nickel deposited in the electrolytic cell or to provide an absorption tower for absorbing chlorine gas generated in the electrolytic cell, and the electrolytic cell 3 may be one tank. Moreover, since Cl ⁻ generated in the cathode chamber 31 is used for oxidizing FeCl _{2 in} the anode chamber 32, the ferric chloride solution can be regenerated by a simple method.

In the above-mentioned embodiment, the case of the batch type has been described, but when the method of the present invention is carried out continuously, for example, the apparatus shown in FIG. 4, that is, the waste liquid, the waste liquid receiving tank 1, the cathode chamber 31, A valve V5 is connected to a pipe T8 connecting the waste liquid receiving tank 1 and the cathode chamber 31 by using a device for continuously flowing the nickel removal process, the anode chamber 32, and the ferric chloride storage tank 6.
A valve V6 is provided in the pipe T9 that connects the denickeling process and the anode chamber 32, and in the cathode chamber 31, when the oxidation-reduction potential of the waste liquid reaches a predetermined value, the opening of the valve V5 is controlled to control the raw material. It is sufficient to control the supply amount of a certain ferric chloride waste liquid, and in the anode chamber 32, when the redox potential of the anolyte reaches a predetermined value, the opening of the valve V6 is controlled so that the anode from the nickel removal step The supply amount of the liquid may be controlled.

[0043]

【Example】

(Example 1) FeCl ₂ 1.7%, Ni 0.7%, Fe
5000 g of a solution containing 46% of Cl _{3 and} having an oxidation-reduction potential of 580 mV was used as a simulated solution of ferric chloride waste solution when an iron-nickel alloy was used as the material to be etched,
Experiments were conducted using the apparatus shown in FIG. At this time, titanium electrodes coated with white metal were used as the cathode 31a and the anode 32a, and the above-mentioned Yumicron film (electrical resistance 0.001 Ωdm ² , water permeability 0.000) was used as the diaphragm 33.
8 cc / cm ² · min or less) was used.

First, 5000 g of the simulated liquid was supplied to the cathode chamber 31, and 5000 g of ferrous chloride liquid was supplied to the anode chamber 32, and the oxidation-reduction potential of the simulated liquid was 4 at an electrolysis voltage of 5V.
Electrolysis was performed until the voltage reached 50 mV (reduction step). The composition of the simulated liquid after the reduction process was FeCl ₂ 41%, Ni 0.
It was 77% and FeCl ₃ 1.1%. After this, cathode chamber 3
The simulated liquid was discharged from No. 2, 42 g of iron (Fe) was added to the liquid, and the mixture was stirred to deposit nickel metal for solid-liquid separation (denickel process). The composition of the simulated solution after nickel separation was FeCl ₂ 43.8%, Ni 5 ppm, FeC
a l ₃ 0.1%, the redox potential was 10 mV. Subsequently, the simulated liquid after nickel separation is supplied to the anode chamber 32, and the simulated liquid (simulated liquid containing nickel) is supplied to the cathode chamber 31.
Was supplied and electrolysis was performed under an electrolysis voltage of 5 V until the oxidation-reduction potential of the simulated solution in the anode chamber reached 750 mV (oxidation step). The amount of simulated liquid after the oxidation process is 5070g
And the composition is FeCl ₃ 50%, FeCl ₂ 0.1
%, And Ni was 10 ppm.

Example 2 FeCl ₂ 4.0%, Cu
Using 5000 g of a solution containing 1.0% and FeCl ₃ 31.6% and having an oxidation-reduction potential of 600 mV as a simulated ferric chloride waste liquid when copper was used as the material to be etched, When the reduction process was performed under similar conditions,
After completion of the process, the composition of the simulated solution was 29.9% FeCl ₂ and C
u 1.1% and FeCl ₃ 1.1%. After that, 53 g of iron (Fe) was added to the simulated liquid discharged from the cathode chamber 32 and stirred, copper metal was deposited, solid-liquid separation was performed, and a copper removal step was performed. Is Fe
The content of Cl _{2 was} 33.3%, the content of Cu was 0%, and the content of FeCl _{3 was} 0%. Subsequently, when an oxidation process was performed under the same conditions as in Example 1, the amount of the simulated liquid after the process was 5100 g,
The composition is 39% FeCl ₃ , 0.1% FeCl ₂ , Cu1.
It was 5 ppm.

(Example 3) FeCl ₂ 1.6%, Ni
5000 g of a solution containing 0.6%, Cr 300 ppm and FeCl ₃ 46.4% and having a redox potential of 585 mV,
The iron-chromium-nickel alloy used as the material to be etched was used as a simulated liquid of ferric chloride waste liquid, and a reduction process was performed under the same conditions as in Example 1. The composition of the simulated liquid after the process was completed. Is FeCl ₂ 41%, Ni 0.75%,
Cr was 350 ppm and FeCl _{3 was} 1.2%. After that, 70 g of iron (Fe) was added to the simulated liquid discharged from the cathode chamber 32 and stirred to precipitate nickel metal,
Since the pH of the simulated liquid becomes 3.5 or more when iron is added, chromium is deposited as hydroxide, and solid-liquid separation of these is carried out and a demetallizing step is carried out. The composition is FeCl ₂ 43.2%, Ni 5
It was ppm, Cr 10 ppm, and FeCl ₃ 0.13%. Subsequently, when the oxidation step was performed under the same conditions as in Example 1, the amount of the simulated liquid after the step was 5090 g,
The composition is 49% FeCl ₃ , 0.1% FeCl ₂ , and Ni1.
It was 2 ppm and Cr 15 ppm.

According to the above experimental example, according to the method of the present invention, the ferric chloride solution can be regenerated without increasing the amount of the solution, and the regenerated ferric chloride solution is Ni (C
Since the u) concentration is as low as 50 ppm or less, it was confirmed that it can be used as an etching solution. It was also confirmed that by controlling the timing of termination of electrolysis by the oxidation-reduction potential, nickel (copper) deposition was suppressed in the reduction process and chlorine gas generation was suppressed in the oxidation process.

(Example 4) Using various Yumicron membranes as the diaphragm 33, the same simulated solution as in Example 1 was used, and the ferric chloride solution was regenerated under the other conditions. The characteristics of the used Umicron film and the nickel concentration in the regenerated ferric chloride solution are shown in FIG. 5 (a). Further, FIGS. 5 (a), 5 (b) and 5 (c) show cases where the same experiment was performed using the same simulated solution as in Examples 2 and 3, respectively.

According to this embodiment, the water permeability is 0.3 cc /
It was confirmed that the nickel concentration, the copper concentration, and the chromium concentration in the regenerated ferric chloride solution could all be reduced to 50 ppm or less by using a diaphragm of cm ² · min or less. It was also confirmed that if the electric resistance is 0.013 Ω · dm ² or less, the time required for electrolysis will not be so long.

In the above-mentioned method of the present invention, the demetallizing step may be carried out by, for example, a method using Ni (Cu, Cr) selective ion exchange resin or a method utilizing the difference in solubility.

[0051]

According to the present invention, when the ferric chloride waste liquid containing the metal forming the material to be etched and ferric chloride is regenerated by electrolysis, it is possible to suppress the increase of the liquid amount by a simple method. The ferric solution can be regenerated.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a ferric chloride liquid regenerating apparatus for carrying out the method of the present invention.

FIG. 2 is a process chart for explaining the method of the present invention.

FIG. 3 is a characteristic diagram showing a relationship between ferric chloride concentration and redox potential, and a relationship between ferrous chloride concentration and redox potential.

FIG. 4 is a configuration diagram showing another example of a ferric chloride liquid regenerating apparatus for carrying out the method of the present invention.

FIG. 5 is a table showing the relationship between the amount of water permeation and electric resistance of the diaphragm and the concentration of nickel (copper, chromium) in the regenerated ferric chloride solution.

[Explanation of symbols]

2 Waste liquid circulation tank 3 electrolysis tank 31 Cathode chamber 31a cathode 32 Anode chamber 32a anode 33 diaphragm 41,43 Redox potential 5 Anolyte circulation tank V1 to V6 valves

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) C23F 1/46

Claims (3)

(57) [Claims] 1. To regenerate ferric chloride liquid from an etching waste liquid containing the metal and ferric chloride after etching a metal forming an etching target material using ferric chloride liquid as an etching liquid In the method of regenerating the ferric chloride solution, electrolyzing the etching waste solution in the cathode chamber of the electrolytic cell divided into a cathode chamber and an anode chamber by a membrane that is substantially impermeable to water while detecting the redox potential , While the ferric chloride slightly remains in the etching waste liquid so that the metal is not deposited, the redox potential becomes the first potential.
In the reduction step of reducing the bulk of the ferric chloride contained in the waste etching solution to ferrous chloride, then removed the etching waste liquid after electrolysis the reduction step is performed outside the cathode chamber, the waste A demetallizing step of separating the metal in, and then introducing the etching waste liquid in which the demetallizing step has been performed into the anode chamber to perform electrolysis while detecting the redox potential ,
Chlorine is added to the etching waste liquid so that chlorine gas is not generated.
With a slight amount of ferrous iron remaining, the redox potential becomes
An oxidation step of oxidizing ferrous chloride contained in the etching waste liquid until the potential reaches , and regenerating the ferric chloride solution.
And a step of regenerating the ferric chloride solution, wherein the reducing step and the oxidizing step are performed simultaneously in the same electrolytic cell. 2. The metal forming the material to be etched is copper,
Nickel, chromium, nickel-iron alloy or iron-nickel
-Salt according to claim 1, characterized in that it is a chromium alloy.
Method of regenerating ferric chloride liquid. 3. The membrane that is substantially impermeable to water is permeable.
It must be a diaphragm with a water content of 0.3 cc / cm 2 · min or less.
Reconstitution of the ferric chloride liquid according to claim 1 or 2, characterized in that
Raw method.