JP2678836B2 - Method of regenerating 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 method for treating a ferric chloride etching waste liquid containing nickel, for example, to regenerate the ferric chloride etching liquid.

[0002]

2. Description of the Related Art As an etching solution for etching nickel materials such as recent Invar materials, a concentration of 47 is generally used.
50 Baume ferric chloride (FeCl ₃₎ solution is used. As can be seen from the following chemical formula 1, the etching waste liquid after etching nickel (Ni) with ferric chloride is a ferric chloride solution containing about 1% nickel, and 2 to 3% of nickel ions commensurate with nickel ions. Ferrous chloride (F
eCl ₂ ) solution.

[0003]

Embedded image In order to recycle the ferric chloride solution by treating such etching waste liquid (ferric chloride waste liquid), the following chemical formula 2 is used.
As shown in Fig. 1, iron scrap is put into the waste liquid, ferric chloride is first converted to ferrous chloride, that is, Fe ³⁺ is converted to Fe.
There is known a method in which nickel is deposited after separation into ²⁺ , separated and removed, and then ferrous chloride is chlorinated to regenerate ferric chloride.

[0004]

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[0005]

However, in the above-mentioned regeneration method, as can be seen from the chemical formula 2, 1 to 5 times as much ferric chloride as the ferric chloride in the waste liquid is re-produced. Therefore, excess ferric chloride is neutralized as shown in Formula 3 and discarded, or excess ferrous chloride is neutralized at the stage where ferrous chloride is produced as shown in Formula 4. I try to discard it.

[0006]

Embedded image

[0007]

Embedded image And if the demand for ferric chloride solution in the market is constant, the amount of ferrous chloride or ferric chloride discarded in the above regeneration cycle reaches about 50% of the returned waste liquid. On the other hand, a high concentration ferric chloride solution is required to etch nickel, so a large amount of iron scrap is required to reduce Fe ³⁺ to Fe ²⁺ .
In this way, discarding a large amount of ferrous chloride or ferric chloride while using a large amount of iron material is
The amount used as a product is unbalanced and is very inefficient.

The present invention has been made under such circumstances, and an object thereof is to provide a method for regenerating a ferric chloride solution with high production efficiency.

[0009]

Means and Actions for Solving the Problems The present invention will be described by taking as an example the treatment of a ferric chloride waste liquid after etching a nickel material. FIG. 1 is a process chart of an example of the present invention,
In the present invention, first, the above waste liquid is subjected to reduction treatment with hydrogen gas using a reduction catalyst in the reduction step. Specifically, a catalyst layer is formed by a reducing catalyst so as to block a passage in the treatment tower, and the waste liquid is allowed to flow from above the catalyst layer to below in the treatment tower, and hydrogen gas is supplied from below. Thus, the ferric chloride waste liquid and hydrogen gas are brought into contact with the reduction catalyst at the same time. In this case, in order to suppress crystallization of ferric chloride, it is desirable to dilute the waste liquid 1.2 to 2 times with pure water, for example. As a result, ferric chloride is reduced to ferrous chloride as shown in Chemical Formula 5, and in the processing liquid discharged from the processing tower, nickel chloride formed during etching of ferrous chloride, hydrochloric acid, and nickel (NiCl
₂ ) and are included.

[0010]

Embedded image Then, in order to remove the hydrochloric acid generated in the reduction step, the treatment liquid is put into a diffusion dialysis tank to perform diffusion dialysis.
As a result, hydrochloric acid is diffused and recovered on the solvent side such as pure water in the diffusion dialysis tank, and hydrochloric acid is removed from the treatment liquid. After that, put iron scrap into this treatment liquid,
Nickel is deposited by a substitution reaction of nickel ionized from nickel chloride with iron (see Chemical Formula 2), and nickel is removed by solid-liquid separation. In this nickel precipitation removal step, for example, an iron scrap whose amount is about 2 to 10 times the nickel content is required under a liquid temperature of 70 to 90 ° C., but the nickel concentration is, for example, 1% with respect to the waste liquid. The amount of iron scrap used is very small as it is very small in front and back.

After that, chlorine gas is passed through the treatment liquid from which nickel has been removed to chlorinate the ferrous chloride and to remove the ferric chloride.
The iron is added, and the ferric chloride solution is concentrated to regenerate a high-concentration ferric chloride solution.

In the above, as the reduction catalyst used in the above-mentioned reduction step, for example, a large number of child particles made of a water-repellent substance are attached to the surface of mother particles made of a platinum group metal, and a part of the child particles are made of the water-repellent substance. What is formed by welding to the base material can be preferably used. The reason is as follows. That is, in the contact region (three-phase interface) of the platinum group metal, hydrogen gas and ferric chloride solution, a reduction reaction occurs, but when hydrogen gas is present on the surface of the water-repellent substance, water is repelled, so that the reaction region is It becomes a contact portion between the mother particles and the child particles.

Here, for example, when platinum group metal particles are simply adhered to a substrate made of a water-repellent substance, only the contact area between each particle and the substrate serves as a reaction region. Since the reaction area is the contact area between the particles and many particles attached to the surface of the particles, the reaction area can be made large. As a result, high catalytic activity equivalent to that of platinum black can be obtained, and the three-phase interface can be obtained. The reaction can be carried out efficiently.

As the platinum group metal in the reduction catalyst, Pt, Ir, Rh, Ru, etc. may be used alone, but an alloy formed by combining two or more of them may be used.

In the present invention, the metal ions to be removed contained in the ferric chloride waste liquid may be metal ions other than nickel.

[0016]

EXAMPLE FIG. 2 is a schematic view showing an example of an apparatus for reducing ferric chloride waste liquor. In this example, a raw material liquid inlet 11 and a treatment liquid outlet 12 are provided at the upper end and the lower end, respectively.
Using a treatment tower 2 having an inner diameter of 10 cm and a height of 1.5 m, a reduction catalyst to be described later is provided near the center thereof, for example, 600 g between two upper and lower mesh bodies made of fluororesin.
A fixed catalyst bed 3 is formed so as to block the passage by filling, and a porous plate 4 that allows only gas to permeate is arranged at the bottom of the processing tower 2, and a hydrogen gas supply unit 5 is provided below the porous plate 4. The reduction processing device is configured by providing the reduction processing device.

Next, the production method of the reduction catalyst will be described. Using a solvent solution of chloroplatinic acid (H ₂ PtCl ₆ · 6H ₂ O), 50 ml of an ethanol solution containing 2 g of Pt and P were added.
The suspension was mixed with 12 g of a suspension in which 4 g of TFE powder was dispersed, and a PTFE cut piece (5 mm in width and 5 to 1 in length) was added to the mixture.
After immersing 200 g of a substrate having a thickness of 0 cm and an average thickness of 100 μm, the substrate is dried, and immersion and drying are repeated 25 to 30 times to obtain a particle layer having an average thickness of about 1.2 μm. Thereafter, this was heated at 280 ° C. for 60 minutes in a hydrogen gas atmosphere furnace,
As a result, the platinum salt is reduced to platinum metal, and a part of the PTFE powder adhering to the surface and the base are welded to each other by softening and melting, whereby a reduction catalyst is obtained.

Here, ferric chloride is 45 to 47%, ferrous chloride is 2 to 3%, and nickel chloride (NiCl ₂ ) is 1 to 2
% Of ferric chloride waste liquid containing 5% of the ferric chloride is diluted, and the waste liquid is diluted 1.2 times with pure water so that ferrous chloride does not crystallize.
When the hydrogen gas was introduced into the treatment tower 2 through the inlet 11 at a flow rate of 0.5 l / h and hydrogen gas was aerated at a flow rate of 4 l / min to carry out the reduction treatment, the treatment liquid taken out from the discharge outlet 12 It contained 0.1% ferric chloride, 30% ferrous chloride, 3% nickel chloride and 7-8% hydrochloric acid.

Therefore, it is supported by this reduction step that almost all of the ferric chloride in the waste liquid was reduced to ferrous chloride.

Thereafter, the treatment liquid was introduced into the treated liquid chamber 61 of the diffusion dialysis tank 6 shown in FIG. 3 at a rate of 1 l / h, and pure water was introduced into the solvent chamber 62 at a flow rate of 1.2 l / h. However, the treatment liquid taken out from the treatment liquid chamber 61 side contained ferrous chloride and nickel chloride, but the hydrochloric acid was significantly reduced. The solvent extracted from the solvent chamber 62 side contained hydrochloric acid and a trace amount of ferrous chloride. Therefore, in this diffusion dialysis tank 6, it can be seen that all of the hydrochloric acid contained in the liquid chamber 61 side diffused into the solvent through the exchange membrane 7 and the hydrochloric acid produced in the reduction treatment step was removed.

Then, into the treatment liquid treated in the diffusion dialysis tank 6, iron scrap having a content of 4 to 5 times the content of nickel ions is charged to deposit and desorb nickel, and then chlorine gas is added to the treatment liquid. Aeration was carried out, and thereby ferrous chloride was chlorinated to ferric chloride and further concentrated to obtain a highly concentrated ferric chloride solution (regeneration solution).

[0022]

As described above, according to the present invention, the second chloride
Since iron is reduced by hydrogen gas to ferrous chloride, in this reduction treatment, ferrous chloride is produced in the same amount as ferric chloride in a molar ratio, and thereafter, metal ions such as nickel ions in the waste liquid are generated. Is deposited and desorbed, and then ferric chloride is chlorinated to form ferric chloride. Therefore, ferric chloride only increases by the amount corresponding to the metal ions, and the regeneration ratio is far higher than that of the conventional method. Low.

Therefore, in the regeneration cycle, an extra second chloride is added.
In addition to producing a small amount of iron, the iron material used is almost consumed only for the precipitation of metal ions, so that the amount of iron used is small, and as a result, it is possible to perform a recycling process without waste. Further, since hydrochloric acid produced during the reduction treatment is recovered by the diffusion dialysis treatment, this is also an effective treatment method.

[Brief description of the drawings]

FIG. 1 is a process chart showing a flow of the present invention.

FIG. 2 is an explanatory diagram showing an example of an apparatus for performing a reduction process.

FIG. 3 is an explanatory diagram showing an example of an apparatus for performing diffusion dialysis treatment.

[Explanation of symbols]

 2 treatment tower 3 catalyst fixed bed 4 porous plate 5 hydrogen gas supply section 6 diffusion dialysis tank

Claims (1)

(57) [Claims] 1. A step of aerating hydrogen in a ferric chloride waste liquor containing metal ions in the presence of a reducing catalyst, thereby reducing ferric chloride to ferrous chloride, and a step obtained by this step. The reduction treatment liquid thus obtained is subjected to diffusion dialysis to separate and remove hydrochloric acid generated during reduction, and iron is reacted with the waste liquid from which hydrochloric acid has been separated and removed in this process to deposit and desorb the metal ions by a substitution reaction. A method for regenerating a ferric chloride solution, comprising: a step; and a step of chlorinating the treatment liquid treated in this step to obtain a ferric chloride solution.