JP3104720B2 - Nickel removal method from nickel-containing iron chloride aqueous solution - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to, for example, 36 nickel-
Invar material such as 64 iron, 42 alloy (Fe: 58% by weight, N
i: 42% by weight), 52 alloy (Fe: 48 to 50% by weight, Ni: 5)
(0 to 52% by weight) of an alloy containing nickel, such as an alloy material, is etched to produce an aqueous solution of ferric chloride used as an etching solution when manufacturing a shadow mask for a television or a lead frame for a semiconductor. This is a method used for the regeneration of waste liquid, and provides a method for efficiently removing nickel from those waste liquids.

[0002]

2. Description of the Related Art An aqueous ferric chloride solution commonly used as an etching solution for precision processing of iron-nickel alloys such as invar and alloy materials is represented by 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, and its etching ability gradually decreases. As a result, the waste liquid becomes difficult to use.

[0003]

[Equation 1] Fe + 2FeCl ₃ → 3FeCl ₂ ‥‥‥ (1)

[0004]

[Equation 2] Ni + 2FeCl ₃ → 2FeCl ₂ + NiCl ₂ ‥‥‥ (2)

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

As these methods, for example, a method in which nickel chloride is crystallized and removed under heat and strong acidity (Japanese Unexamined Patent Publication No.
No. 2,507,764), a method for removing precipitates as nickel glyoxime by adding glyoximes such as dimethylglyoxime (JP-A-59-190367) or a method for adding and removing massive metallic iron (JP-A-59-121).
123) has been proposed.

Further, the present inventors have proposed a more excellent method of adding iron powder of 100 mesh or more to an aqueous solution of ferrous chloride containing nickel (Japanese Patent Laid-Open No. 62-19 / 1987).
No. 1428) and a method of adding iron powder having a specific surface area of 1 m ² / g or more to an aqueous solution of ferrous chloride containing nickel (Japanese Patent Application Laid-Open No. 3-253584). On the other hand, a method of removing chromium and nickel from an aqueous solution of iron chloride containing chromium and nickel has also been proposed (Japanese Patent Publication No. 3-2233).
issue).

[0008]

In the above-described method for removing nickel from an aqueous solution of iron chloride, it is required that the reaction proceed promptly with a small amount of iron powder used relative to nickel. The method proposed above is industrially excellent as a method capable of sufficiently removing nickel in an aqueous iron chloride solution, but is not sufficient in terms of the amount of iron powder used and the reaction rate, and the reaction time is not sufficient. Tended to be longer. In view of the above problems, the present inventors have conducted intensive studies to further improve the previously proposed method for removing nickel from 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 aqueous solution of iron chloride containing nickel and composed of ferric chloride and ferrous chloride, and added the iron material to the aqueous solution. After the ferric chloride is changed to ferrous chloride, nickel removal proceeds rapidly by adding iron powder to an aqueous solution obtained without separating by-produced iron hydroxide or hydrous iron oxide. The inventors have found that the present invention has been completed.

[0010] That is, the present invention is to provide an iron chloride solution containing nickel containing iron, the ferric chloride present in the aqueous solution is changed into ferrous chloride, and then the presence of iron hydroxide or iron hydroxide containing iron is added. The present invention relates to a method for removing nickel from a nickel-containing aqueous solution of iron chloride, wherein iron powder is added below to remove nickel. Hereinafter, the present invention will be described in detail.

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

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

[0013]

[Equation 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]

[Formula 4] Fe + 2HCl → FeCl ₂ + H ₂ (4) In this case, nickel in the aqueous solution partially precipitates metallic nickel, but most of the nickel is present in the liquid as ions.

The shape of the iron material to be used may be any shape, for example, iron pieces, iron lumps, bar-like irons and the like. The amount of the iron material used is an excess of the theoretical amount required to convert ferric chloride in the aqueous ferric chloride solution to ferrous chloride, and is usually 1 to 1 with respect to the ferric chloride in the aqueous ferric chloride solution. It is preferable to use 10 times mol. The reaction temperature is preferably from room temperature to 100 ° C, more preferably from 40 to 100 ° C. The reaction time can be selected variously depending on conditions such as the amount of the liquid, the type of the iron material, the amount of the iron material, the reaction temperature and the like. Completion of the reaction can be confirmed by analyzing the concentration of ferrous chloride or measuring the oxidation-reduction potential with an ORP meter or the like.

The iron hydroxide or the iron oxide hydrate present in the aqueous iron chloride solution when the iron powder is added is produced as fine particles as a result of the reaction between the aqueous iron chloride solution and 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, these iron hydroxides or hydrated iron hydroxides are intentionally present without being removed, and are even more actively formed, without separating the by-products or the generated iron hydroxides or hydrated iron hydrates. The method is characterized in that iron powder is added to an aqueous solution in which is present to remove nickel.

The content of iron hydroxide or iron hydroxide in the aqueous iron chloride 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 hydrated iron hydroxide is 0.
When the amount is less than 05% by weight, the effect of the present invention is not exhibited. On the other hand, when the amount exceeds 10% by weight, handling of the aqueous solution becomes difficult due to the slurry of iron hydroxide or iron oxide hydroxide.

In order to make the content of iron hydroxide or hydrated iron hydroxide in the aqueous solution of iron chloride a preferable content, it is preferable to positively contact the mixed solution of the aqueous solution of iron chloride and iron powder with oxygen during the reaction. . Examples of the method of bringing into contact with oxygen include a method of blowing oxygen or a method of circulating a reaction solution under an oxygen atmosphere, usually under an air atmosphere. Oxygen or an oxygen mixture can be used as the oxygen source. 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,
When using any method of circulating the liquid, even after the reduction of ferrous chloride is completed, by continuing the reaction for several hours, the content of iron hydroxide or hydrated iron oxide in the liquid is preferable. Content.

If the content of iron hydroxide or iron oxide hydroxide in the aqueous solution after the reaction is less than 0.05% by weight, nickel hydroxide or iron oxide hydroxide prepared separately is added to remove nickel. Can also be performed. In this case, the amount of the iron hydroxide or the iron oxide hydroxide to be added is within the range not exceeding 10% by weight in the aqueous iron chloride solution as described above.

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

The iron powder to be added to the aqueous ferrous chloride solution includes:
Fine materials are good, and if they are rough, the removal efficiency is not good. The particle size is preferably 100 mesh passes or more,
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, since the removal efficiency is good. As the reaction temperature,
Room temperature to 100 ° C is preferred, and more preferably 40 to 90 ° C.
° C. The reaction time can be variously selected depending on the reaction conditions, but is preferably 1 hour or more, more preferably 2 to 8 hours at a reaction temperature of 80 ° C. The amount of the iron powder to be added depends on the reaction conditions and the nickel content, but is 1 mol or more, preferably 3 to 7 mol per mol of nickel.

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

[0024]

[Equation 5] 2FeCl ₂ + Cl ₂ → 2FeCl ₃ ... (5)

[0025]

In the present invention, it is not clear why the presence of iron hydroxide or hydrated iron hydroxide in the aqueous ferrous chloride solution promotes the removal of nickel. However, the fine particles of iron oxide or hydrated iron oxide present in the aqueous solution are not clear. It is presumed that since the surface has high basicity, nickel in the aqueous solution reacts on the surface of the particles to form nickel hydroxide, so that nickel removal is promoted.

[0026]

The present invention will be described below in more detail with reference to examples and comparative examples. Note that “%” in each example represents “% by weight”.

Example 1 A dilute aqueous solution of ferric chloride etching waste liquid (composition: FeCl ₃ ; 3) was placed in a 5-liter glass bottle having an outlet at the lower side.
0.52%, FeCl ₂ ; 7.81%, Ni; 7290ppm, HCl; 0.04%) 4 liters (5800 g) and 930 g of iron pieces were charged, the reaction temperature was adjusted to 70 ° C. with a temperature controller, and a pump was used under an air seal. When the reaction was carried out for 4 hours by circulating the liquid, the concentration of FeCl _{3 in} the aqueous solution after the reaction became 0.1% or less. When the reaction was further performed 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; 5830 ppm. Without filtering 700 g of the above reaction solution,
A 1-liter three-necked flask equipped with a cooling pipe, a thermometer, and a stirrer was charged, and had a particle diameter of 100 mesh pass and a particle diameter of 251 mesh or more was 55%.
15.53 g of iron powder having a specific surface area of 3.01 m ² / g
(4.00 moles relative to nickel), and reacted at 80 ° C. for 2 hours in an air atmosphere with stirring. After the obtained reaction solution was filtered through 5B filter paper, the nickel content in the filtrate was 56 ppm, and the pH was 3.1.

Comparative Example 1 One liter of the reaction solution obtained by reacting the waste ferric chloride etching solution of Example 1 with iron pieces was filtered with 5B filter paper. 15.7 iron powder as in Example 1 was added to 700 g of the obtained filtrate.
4 g (4.00 times the molar amount of nickel) was charged and reacted at 80 ° C. for 2 hours under an air atmosphere with stirring. After the obtained reaction solution was filtered through 5B filter paper, the nickel content in the filtrate was 187 ppm, and the pH was 3.2.

Example 2 In Example 1, the liquid was circulated and the air flow was 0.5 l / min.
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 rate of 1. The FeCl ₃ concentration in the aqueous solution after the reaction became 0.1% or less. When the reaction was further performed 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; 6023 ppm. Without filtering 700 g of the above reaction solution,
16.0 g of the same iron powder as in Example 1 (with respect to nickel 4.00 g)
When the nickel was removed and filtered in the same manner as in Example 1, 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. This is a significant contribution to the industry.

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Claims (1)

(57) [Claims] 1. An iron material is added to an aqueous solution of nickel-containing iron chloride to convert ferric chloride present in the aqueous solution to ferrous chloride, and then iron powder is added in the presence of iron hydroxide or hydrous iron oxide. And removing nickel from the nickel-containing aqueous solution of iron chloride.