JPH05255869A - Method for removing nickel in aqueous nickel-containing iron chloride solution - Google Patents

Abstract

PURPOSE:To selectively and efficiently remove Ni in an aq. iron chloride soln. by adding an iron material to an aq. Ni-contg. iron chloride soln. to convert FeCl3 to FeCl2 and adding powdery iron to the soln. in the presence of iron hydroxide to remove Ni. CONSTITUTION:An appropriate amt. of an iron material (iron pieces, iron blocks, etc.) is added to an aq. soln. contg. FeCl2, FeCl3 and Ni such as the waste soln. generated when an Ni alloy is etched with an aq. FeCl3 soln. to convert FeCl3 to FeCl2, then about 0.5-10wt.% of iron hydroxide or hydrated iron oxide is incorporated into the soln., and an appropriate amt. of powdery iron (about 15-350 mesh) is added to deposit the Ni on the iron powder in the soln. Consequently, Ni in an aq. iron chloride soln. is selectively and efficiently removed in a short period.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to, for example, 36 nickel-
Amber material such as 64 iron, 42 alloy (Fe: 58% by weight, N
i: 42 wt%), 52 alloy (Fe: 48-50 wt%, Ni: 5
0 to 52% by weight) alloy material such as nickel alloy is etched to produce a ferric chloride aqueous solution used as an etching solution when manufacturing a television shadow mask or a lead frame for a semiconductor. It is a method used for recycling waste liquids and provides a method for efficiently removing nickel in those waste liquids.

[0002]

2. Description of the Related Art An aqueous solution of ferric chloride, which is widely used as an etching solution for precision processing of iron-nickel alloys such as amber and alloy materials, has the following reaction formulas (1) and (2). In addition, as it is used for etching, trivalent iron (ferric chloride) in the aqueous solution is reduced to divalent iron (ferrous chloride), and nickel also accumulates, gradually decreasing its etching ability. Finally, it becomes a waste liquid that is difficult to use.

[0003]

[Formula 1] Fe + 2FeCl ₃ → 3FeCl ₂ (1)

[0004]

[Formula 2] Ni + 2FeCl ₃ → 2FeCl ₂ + NiCl ₂ (2)

From the viewpoint of economy and resource saving, it is desirable to recycle and recycle the etching waste liquid. However, in the etching waste liquid, nickel, which lowers the etching ability as the etching liquid, is usually several thousand ppm to 1 ppm.
There is about 10,000 ppm, and it is necessary to suppress the nickel content to 100 ppm or less in order to reuse the etching waste liquid. Therefore, various attempts have hitherto been made to remove nickel from the etching waste liquid.

As these methods, for example, a method of crystallizing and removing nickel chloride under heating and concentration under strong acidity (JP-A-59-59).
No. 250764), glyoximes such as dimethylglyoxime are added to precipitate and remove as nickel glyoxime (JP-A-59-190367) or lumpy metallic iron is added and removed (JP-A-59-121).
No. 123) has been proposed.

Furthermore, the inventors of the present invention, as a more superior method, add iron powder of 100 mesh or more to an aqueous ferrous chloride solution containing nickel (Japanese Patent Laid-Open No. 62-19).
1428), and a method of adding iron powder having a specific surface area of 1 m ² / g or more to a nickel-containing ferrous chloride aqueous solution (JP-A-3-253584). On the other hand, a method for removing chromium and nickel from an iron chloride aqueous solution containing chromium and nickel is also proposed (Japanese Patent Publication No. 3-2233).
issue).

[0008]

In the above method for removing nickel in an aqueous solution of iron chloride, it is required that the reaction be promptly proceeded with a small amount of iron powder used with respect to nickel. The previously proposed method is industrially excellent as a method capable of sufficiently removing nickel in an iron chloride aqueous solution, but the amount of iron powder used and the reaction rate are not yet sufficient, and the reaction time Tended to be long. In view of the above problems, the present inventors have conducted earnest studies to further improve the previously proposed method for removing nickel in an aqueous solution of iron chloride.

[0009]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors added an iron material to an iron chloride aqueous solution containing nickel and consisting of ferric chloride and ferrous chloride, After changing ferric chloride from ferric chloride to ferrous chloride, adding iron powder to the resulting aqueous solution without separating the by-produced iron hydroxide or hydrous iron oxide will rapidly remove nickel. It was found that the present invention has been completed.

That is, according to the present invention, an iron material is added to an iron chloride aqueous solution containing nickel to change ferric chloride present in the aqueous solution to ferrous chloride, and then the presence of iron hydroxide or hydrous iron oxide is present. The present invention relates to a method for removing nickel in a nickel-containing iron chloride aqueous solution, which comprises adding iron powder to the bottom to remove nickel. Hereinafter, the present invention will be described in detail.

In the present invention, the iron chloride aqueous solution containing nickel means an aqueous solution containing ferrous chloride, ferric chloride and nickel, such as a waste liquid obtained by etching a nickel alloy with a ferric chloride aqueous solution.

In the method for removing nickel of the present invention, first, an iron material is added to an iron chloride aqueous solution containing nickel, and ferric chloride is changed to ferrous chloride as shown in formula (3).

[0013]

[Formula 3] 2FeCl ₃ + Fe → 3FeCl ₂ (3)

When hydrochloric acid is contained in the aqueous solution,
As shown in formula (4), the hydrochloric acid produces ferrous chloride.

[0015]

[Equation 4] Fe + 2HCl → FeCl ₂ + H ₂ (4) In this case, most of the nickel in the aqueous solution is a precipitate of metallic nickel, but most of it exists as ions in the liquid.

The iron material to be used may have any shape, and examples thereof include an iron piece, an iron ingot, and a rod-shaped iron. The amount of the iron material used is an excess of the theoretical amount necessary to change ferric chloride in the ferric chloride aqueous solution to ferrous chloride, and is usually 1 to 1 with respect to ferric chloride in the ferric chloride aqueous solution. It is preferable to use a 10-fold molar amount. The reaction temperature is preferably room temperature to 100 ° C, more preferably 40 to 100 ° C. The reaction time can be variously selected depending on conditions such as the liquid amount, the type of iron material, the amount of iron material, the reaction temperature and the like. Completion of the reaction can be confirmed by analyzing the ferrous chloride concentration or measuring the redox potential with an ORP meter or the like.

The iron hydroxide or hydrous iron oxide present in the iron chloride aqueous solution when the iron powder is added is by-produced as fine particles as the iron chloride aqueous solution reacts with the iron material. Conventionally, these by-products have been removed by filtration or the like and used in the next step. However, in the present invention, those iron hydroxides or hydrous iron oxides are intentionally present without being removed, and are further actively produced, and by-products or produced iron hydroxides or hydrous iron oxides are not separated, and Fe is added to an aqueous solution in which nickel is present to remove nickel.

The content of iron hydroxide or hydrous iron oxide in the iron chloride aqueous solution is preferably 0.05% by weight to 10% by weight, more preferably 0.1% by weight to 2% by weight. .. The content of iron hydroxide or hydrous iron oxide is 0.
If the amount is less than 05% by weight, the effect of the present invention is not exhibited. On the other hand, if the amount is more than 10% by weight, it becomes difficult to handle the aqueous solution due to the slurry of iron hydroxide or hydrous iron oxide.

In order to obtain a preferable content of iron hydroxide or hydrous iron oxide in the iron chloride aqueous solution, it is preferable that the mixed solution of the iron chloride aqueous solution and the iron powder and oxygen be positively contacted during the reaction. .. Examples of the method of contacting with oxygen include a method of blowing oxygen, a method of circulating a reaction solution in an oxygen atmosphere, or in a normal atmosphere. As the oxygen source, oxygen or an oxygen mixture can be used. Examples of the oxygen mixture include air and a mixture of oxygen and an inert gas. It is preferable to use air because it is inexpensive. Also, a method of blowing oxygen,
In the case of using either method of circulating the liquid, even after the reduction of ferrous chloride is completed, by continuing the reaction for several more hours, the iron hydroxide or hydrous iron oxide content in the liquid is preferable. It can be the content.

When the content of iron hydroxide or hydrous iron oxide in the aqueous solution after the reaction is less than 0.05% by weight, nickel hydroxide is removed by adding separately prepared iron hydroxide or hydrous iron oxide. You can also do In this case, the amount of iron hydroxide or hydrous iron oxide added is, in the same manner as described above, such that the content in the aqueous iron chloride solution does not exceed 10% by weight.

When iron powder is added to the ferrous chloride aqueous solution containing iron hydroxide or hydrous iron oxide prepared as described above, nickel in the aqueous solution mainly adheres to the iron powder, Can be easily removed by filtration or the like. The action of the iron powder at this time is not clear, but the following can be considered. 1) Formation of nickel hydroxide due to increase in pH due to reaction with a very small amount of free acid. 2) Precipitation of nickel metal on the surface of metallic iron due to the difference in ionization tendency with iron.

As the iron powder added to the ferrous chloride aqueous solution,
Fine ones are good, and coarse ones are not good at removing efficiency. The particle size is preferably 100 mesh pass or more, and 150 to
A 350 mesh pass is more preferred. Further, it is preferable to use a material having a specific surface area of 1 m ² / g or more because the removal efficiency is good. As the reaction temperature,
Room temperature to 100 ° C is preferable, and more preferably 40 to 90.
℃. The reaction time can be variously selected depending on the reaction conditions, but when the reaction temperature is 80 ° C., it is preferably 1 hour or longer, more preferably 2 to 8 hours. The addition amount of the iron powder depends on the reaction conditions and the nickel content, but is 1 time mol or more, preferably 3 to 7 times mol, relative to nickel.

The ferrous chloride aqueous solution from which nickel has been removed by the above method can be chlorinated as shown in formula (5) and reused as a ferric chloride aqueous solution.

[0024]

[Formula 5] 2FeCl ₂ + Cl ₂ → 2FeCl ₃ (5)

[0025]

In the present invention, the reason why the removal of nickel is promoted by the presence of iron hydroxide or hydrous iron oxide in the ferrous chloride aqueous solution is not clear, but fine particles of iron oxide or hydrous iron oxide present in the aqueous solution are not clear. It is presumed that since the surface is highly basic, nickel in the aqueous solution reacts on the surface of the particles to form nickel hydroxide, which promotes nickel removal.

[0026]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. In addition, "%" in each example represents "weight%."

Example 1 In a 5 liter glass bottle having an outlet at the bottom of the side surface, a dilute aqueous solution of ferric chloride etching waste liquid (composition: FeCl ₃ ; 3
0.52%, FeCl ₂ ; 7.81%, Ni; 7290ppm, HCl; 0.04%) 4 liters (5800g) and iron pieces 930g were charged, the reaction temperature was adjusted to 70 ° C with a temperature controller, and a pump was used under air sealing. When the liquid was circulated and the reaction was carried out for 4 hours, the FeCl ₃ concentration in the aqueous solution after the reaction was 0.1% or less. Furthermore, when the reaction was carried out for 4 hours, the composition of the obtained liquid was FeCl ₃ ;
1% or less, FeCl ₂ ; 41.2%, iron oxide and hydrous iron oxide; 1.0%,
Ni was 5830 ppm. 700 g of the above reaction solution was not filtered,
It was put into a 1-liter three-necked flask equipped with a cooling tube, a thermometer, and a stirrer, and 55% had a particle size of 100 mesh pass and a particle size of 251 mesh or more,
15.53 g of iron powder having a specific surface area of 3.01 m ² / g
(4.00 moles relative to nickel) was charged and reacted at 80 ° C. for 2 hours in an air atmosphere while stirring. The nickel content in the filtrate after filtering the obtained reaction liquid through 5B filter paper was 56 ppm, and the pH was 3.1.

Comparative Example 1 1 liter of the reaction solution obtained by reacting the ferric chloride etching waste liquid of Example 1 with iron pieces was filtered with 5B filter paper. Iron powder similar to that in Example 1 was added to 15.7 g of the obtained filtrate (700 g).
4 g (4.00 moles relative to nickel) was charged and reacted at 80 ° C. for 2 hours in an air atmosphere while stirring. The nickel content in the filtrate after filtering the obtained reaction liquid through 5B filter paper was 187 ppm, and the pH was 3.2.

Example 2 In Example 1, the liquid was circulated and air was supplied at 0.5 l / min.
When the reaction was carried out for 4 hours under the same conditions except that the reaction was carried out while forcibly blowing into the solution at a ratio of, the concentration of FeCl _{3 in} the aqueous solution after the reaction was 0.1% or less. Furthermore, when the reaction was carried out for 2 hours, the composition of the obtained liquid was FeCl ₃ ;
1% or less, FeCl ₂ ; 40.55%, iron oxide and hydrous iron oxide; O.5%,
Ni was 6023 ppm. 700 g of the above reaction solution was not filtered,
The same iron powder as in Example 1 16.0 g (vs. nickel 4.00)
When the nickel content was 65 ppm and the pH was 3.2, the nickel content in the obtained filtrate was 65 ppm and the pH was 3.2.

[0030]

According to the method of the present invention, nickel in an aqueous iron chloride solution can be selectively and efficiently removed in a short time, and an aqueous ferric chloride solution can be easily regenerated from an etching waste liquid such as a nickel alloy. Because it can, it is a great contribution to industry.

Claims (1)

[Claims] 1. An iron powder is added to an aqueous iron chloride solution containing nickel to change ferric chloride present in the aqueous solution to ferrous chloride, and then iron powder is produced in the presence of iron hydroxide or hydrous iron oxide. A method for removing nickel from a nickel-containing iron chloride aqueous solution, which comprises adding nickel to remove nickel.