JP2965457B2 - Regeneration method of iron chloride waste liquid containing nickel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an iron chloride-based waste liquid containing nickel discharged from a manufacturing process of a shadow mask, a lead frame, and the like.
The present invention relates to a method for separating and recovering nickel and iron components from an etching solution containing ferric chloride, ferrous chloride and hydrochloric acid in a circulation step, and recycling the recovered solution as a regenerating solution.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Unexamined Patent Application Publication No.
In the publication, a solution containing iron and nickel having no etching ability is targeted, an oxime reagent is added to the solution, the composition containing nickel is modified into a precipitation complex salt, and the composition containing iron is After remaining water-soluble without reacting, only the composition containing the iron was separated by a filtration method,
A method of regenerating a solution containing ferric chloride having an etching ability by reacting the separated composition containing iron with chlorine gas is disclosed.

In such a method using an oxime reagent, the iron component in the liquid gradually increases as the amount of iron dissolved from the metal plate by etching increases. Therefore, the difference in the ionization tendency of the metal element is used to reduce copper and the like. Similarly to the so-called cementation method, the solution after the precipitation of the nickel complex salt contains ferrous chloride as a main component. Therefore, in order to regenerate as an etching solution, it is necessary to further blow chlorine gas, and the solution becomes a highly concentrated solution in a short period of time. . Furthermore, in this method, since the separated precipitate is a nickel complex salt, it cannot be used effectively as it is at present, and the complex salt has to be chemically treated to recover metallic nickel again. Absent.

Japanese Patent Application Laid-Open No. Sho 59-21947 discloses that
Using an organic solvent such as neutral phosphate ester
FeCl ₃ and HCl are selectively extracted from the aqueous solution containing ions and Cl ions, and the organic solvent containing these iron chloride complexes is back-extracted with water. It is disclosed that _three liquids are collected.

[0005] In this method, there is a problem that a concentration step is required to recycle the regenerated liquid from the back-extraction liquid, and a wastewater treatment facility is required. Have.

[0006]

As a method for electrolytically treating an etching waste liquid different from the above two methods, Japanese Patent Laid-Open No.
Japanese Patent Application Laid-Open No. 1-104092 discloses that an oxidation waste liquid containing a ferrous salt and containing a ferrous salt as an active ingredient is supplied to an anode chamber of an electrolytic cell partitioned by an ion exchange membrane to continuously oxidize and regenerate. It has been disclosed. According to this method, the reaction from ferrous iron to ferrous iron can be performed with a current efficiency of almost 100%.

However, in this method, cations, particularly divalent nickel, in the waste liquid to be regenerated cannot be moved to the cathode side because the membrane used is an anion exchange membrane.

Further, in the embodiment of the publication, FeCl ₃ is added to keep the NiCl ₂ at a constant concentration. In this method, it is necessary to discharge an increasing iron chloride solution and perform a separate treatment. Further, the ion-exchange membrane used is relatively expensive and has poor durability, handling is complicated, and there is a difficulty in practicality.

Therefore, the present inventors previously cooled an iron chloride-based solution containing nickel, crystallized and separated a crystal mainly composed of ferric chloride, and used the liquid after the crystal separation as a cathode of an electrolytic cell. The iron-nickel alloy is electrolytically deposited and the solution after the alloy deposition is transferred to the anode side, and the ferrous chloride contained therein is electrolytically oxidized to ferric chloride while chlorine gas generated on the anode side is removed. Oxidize a different iron chloride-based solution containing nickel as the oxidizing agent, remove the solution after chlorine component separation from the electrolytic cell,
It has been proposed to regenerate an iron chloride solution by dissolving the iron chloride crystal (Japanese Patent Application No. 5-220114, September 1993).
On March 3).

According to such a method, nickel-containing iron chloride waste liquid can be efficiently regenerated while reducing power consumption. However, when the method is examined in more detail, since ferrous iron is once converted to trivalent iron and then returned to divalent iron again in the electrolysis stage, it still has a wasteful portion in terms of electric power.

It is therefore an object of the present invention to regenerate nickel chloride-containing waste liquid containing nickel at a much lower power consumption and to recover nickel at a high recovery rate.

[0012]

The present invention solves the above problems,
(i) adjusting the hydrochloric acid concentration of the iron chloride solution containing nickel,
(ii) Crystallize and separate the crystal mainly composed of nickel chloride,
ii) electrolytically reducing the separated crystals to electrolytically deposit an iron-nickel alloy, (iv) concentrating the liquid after crystal separation and evaporating and separating hydrogen chloride, and (v) adjusting the concentration of the concentrated liquid. The problem was solved by using an iron chloride-based regenerating solution.

When the metal concentration of the iron chloride waste liquid discharged from the manufacturing process of a shadow mask or the like is not so high as required for efficiently obtaining crystals during the crystallization treatment of (ii) above, Before the adjustment of the hydrochloric acid concentration in (i) above, it is preferable to concentrate the iron chloride-based solution containing nickel. It is more preferable to use the steam generated at that time for adjusting the concentration of the concentrated solution of the above (v).

In the electrolytic treatment of (iii), chlorine gas generated on the anode side of the electrolytic cell is used as an oxidizing agent to oxidize an iron chloride-based solution other than the solution used in the series of regeneration processes. It would be convenient.

It is preferable to use the hydrogen chloride generated during the concentration treatment of the above (iv) for adjusting the hydrochloric acid concentration of the above (i).

[0016]

The hydrochloric acid concentration in the nickel chloride-containing waste liquid discharged in the manufacturing process of a shadow mask or the like is generally very low compared to the hydrochloric acid concentration adjusted and concentrated in the first step of the present invention. Since there is some (about 0.1% concentration), a start-up process is first performed to increase the concentration to a predetermined level. Here, the predetermined level is a level that does not hinder the industrial operation for performing the following hydrochloric acid concentration adjustment. In the preconcentration, various known concentration processes can be used, but the simplest process of heating the liquid to generate steam is preferable because the generated steam can be used for dilution in the final stage.

In the pre-concentrated iron chloride solution, (i)
The concentration of hydrochloric acid in the liquid is adjusted by contacting the vapor of hydrogen chloride generated during the concentration treatment of v). Its concentration is about 10% as HCl. It is known that when the liquid is cooled below the temperature at which iron chloride and nickel chloride become saturated under this hydrochloric acid concentration, nickel chloride crystallizes.

The solution whose acid concentration has been adjusted is cooled, and crystals mainly composed of nickel chloride are precipitated and separated. Below the temperature at which the nickel chloride in the solution becomes saturated, for example, about 2
Cool to 0 ° C.

The precipitated crystals are led to the cathode side of the electrolytic cell. On the cathode side, iron ions and nickel ions are reduced and electrodeposited, and metals are recovered. For example, DSE on the anode
Using a titanium plate as an electrode (RuO ₂ / Ti) and a cathode, electrolysis is performed by a diaphragm electrolysis method at a current density of 7.5 A / dm ² and a voltage of about 3.5 V. A polyester filter cloth is used for the diaphragm, and the temperature of the electrolytic solution can be set to about 70 ° C.

The liquid after crystal separation is concentrated again to evaporate hydrogen chloride. The enrichment method is similar to the above pre-enrichment,
The simplest process of heating the liquid to generate steam is sufficient. The use of the generated hydrogen chloride for the initial adjustment of the concentration of hydrochloric acid is as described above.

The liquid obtained by evaporating hydrogen chloride is diluted with steam generated during preconcentration to obtain an iron chloride-based regenerated etchant.

If the chlorine gas generated during the electrolysis is led to the etching step, it can be used as an oxidizing agent for regenerating iron chloride, which is an effective etching component.

[0023]

The present invention will be described more specifically with reference to the following examples.

From the start-up etching step, 12.6 g / l of a divalent iron component, 265 g / l of a trivalent iron component, and 1 nickel component
2,000 g of an etchant having a specific gravity of 1.543 and a composition of 3.9 g / liter and a chlorine component of 525 g / liter.
, and concentrated under reduced pressure at 120 ° C., 940 ml of water vapor corresponding to liquid, 23.8 g / liter of divalent iron component, 500 g / liter of trivalent iron component, nickel component 2
1060 ml of a concentrate having a composition of 6.2 g / l and a chlorine component of 966.9 g / l was obtained. To the concentrate, 1000 ml of 35% hydrochloric acid (specific gravity: 1.18) was added, and the mixture was filtered at 20 ° C. (cooling crystallization) to obtain 208.08 g of crystals and a divalent iron component of 1.0 g / liter, trivalent. 261.8 g / liter of iron component and 2.63 g /
1975 ml of a filtrate having a specific gravity of 1.545 and a composition of 676.6 g / liter of a chlorine component was obtained.

[0025] In flow conceptually shown in Example Figure 1, the etching process is taken out 2020ml an etchant having the same composition as the start-up, then concentrated under reduced pressure at 120 ° C. (first
Water vapor corresponding to 1060 ml liquid, 2
Trivalent iron component 26.5 g / liter, trivalent iron component 55
A 960 ml concentrated liquid having a composition of 7.6 g / liter, a nickel component of 29.3 g / liter, and a chlorine component of 1069.1 g / liter was obtained.

On the other hand, the filtrate obtained by the cooling crystallization at the start-up is concentrated under reduced pressure at 120 ° C., and the vapor of hydrogen chloride is brought into contact with and absorbed by the concentrated solution to adjust the acid concentration. 13.8 g / liter of iron component, 289.4 g / liter of trivalent iron component, and 15.2 nickel component
1850 ml of an acid addition liquid having a composition of g / l and a chlorine component of 733.6 g / l was obtained. 20 ° C
The mixture was cooled and filtered to 7.64% of the divalent iron component, 9.39% of the trivalent iron component, 6.63% of the nickel component, and 3 of the chlorine component.
333.0 g of a crystal having a composition of 6.0%, a trace amount of a divalent iron component, a trivalent iron component of 281 g / liter,
3.5g / liter nickel component, 695g / chlorine component
And separated into 1780 ml of filtrate consisting of 1 liter of composition.

The crystals obtained by the cooling crystallization were subjected to 130.2 g / liter of a divalent iron component and 50.8 g of a nickel component.
Per liter of an electrolytic solution having a specific gravity of 1.30 having a composition of 226.7 g / liter of chlorine component and 138.8 g / liter of divalent iron component and 31.3 g of trivalent iron component.
/ Liter, nickel component 66.3 g / liter, chlorine component 296 g / liter, specific gravity 1.437
The electrolytic solution is returned to the cathode side of the electrolytic cell, and electrolysis is performed.
8 g were obtained. Examination of the composition of the Fe-Ni alloy revealed that N
The i-content was 28% by weight. The power required for the electrolysis was 4.5 Wh per gram of the recovered metal. When the chlorine gas generated on the anode side was absorbed in 20 l of the etchant in the absorption tower, the divalent iron component was 4.8 g / liter, the trivalent iron component was 272.8 g / liter, and the nickel component was 13.9 g.
Per liter and a chlorine component of 529.9 g / liter, and could be returned to the etching step as a regenerated etchant.

On the other hand, the filtrate obtained by cooling crystallization is again
After concentration at 20 ° C. (second stage concentration) and separation of hydrogen chloride vapor, trace amounts of divalent iron component and trivalent iron component 5
890 ml of a concentrated liquid having a composition of 62.0 g / l, a nickel component of 7.0 g / l, and a chlorine component of 1018.3 g / l was obtained. This concentrated solution is diluted using steam obtained in the first-stage concentration, and the trivalent iron component 256.5 is used.
g / liter, nickel component 3.2 g / liter, chlorine component 482.3 g / liter, specific gravity 1.4
27 in 1950 ml was obtained. This was returned to the etching process as a regeneration etchant.

Although the above operation was carried out as a batch process, it is preferable to carry out continuous treatment industrially as shown in FIG.

[0030]

As is apparent from the above description,
The present invention has the following effects.

That is, only the dissolved metal component can be recovered from the etchant circulated in the etching step (closed), and the composition of the crystal to be sent to the electrolytic step is set to N.
i: Fe ≒ 1: 3, so that in the electrolytic process

[0032]

(Equation 1)

[0033]

(Equation 2)

The unnecessary power consumption due to the above reaction can be eliminated. Japanese Patent Application No. 5-220 previously proposed by the present inventors.
Table 1 shows a comparison with the technology disclosed in Japanese Patent No. 114.

[0035]

[Table 1]

[Brief description of the drawings]

FIG. 1 is a schematic flow chart showing one regeneration step of the present invention.

[Explanation of symbols] 1 etching tank 2 electrolytic tank 3 absorption tower

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C23F 1/46 C02F 1/461

Claims (5)

(57) [Claims] (1) adjusting the hydrochloric acid concentration of an iron chloride-based solution containing nickel, (ii) crystallizing and separating a crystal mainly containing nickel chloride, and (iii) electrolytically reducing the separated crystal. Electrolytic deposition of an iron-nickel alloy, (iv) concentrating the liquid after crystal separation and evaporating and separating hydrogen chloride, and (v) adjusting the concentration of the concentrated liquid to be an iron chloride-based regenerated liquid. A method for regenerating an iron chloride waste liquid. 2. The method according to claim 1, wherein prior to the step (i) of adjusting the hydrochloric acid concentration, the iron chloride-based solution containing nickel is concentrated. 3. An iron chloride-based solution different from the solution used in the series of regeneration processes, using chlorine gas generated on the anode side of the electrolytic cell as the oxidizing agent in the electrolytic treatment of (iii). The regeneration method according to claim 1, wherein the oxidation is performed. 4. The method according to claim 1, wherein the hydrogen chloride generated during the concentration treatment in (iv) is used for adjusting the hydrochloric acid concentration in (i). 5. The method according to claim 5, wherein the water vapor generated during the preconcentration is converted to the water vapor.
3. The method according to claim 2, wherein the method is used for adjusting the concentration of the concentrated solution of (v).