JP2002155383A - Method for refining iron chloride aqueous solution and the iron chloride aqueous solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for refining an iron chloride aqueous solution by which cobalt ions as impurities contained in the iron chloride aqueous solution can be removed, and the aqueous solution can be regenerated, and to provide the iron chloride aqueous solution obtained by the refining, and free from impuritis. SOLUTION: Nickel or cobalt ions contained in an iron chloride aqueous solution are precipitated and removed in an acidic region by using a sulfide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is widely used as a dye reducing agent (ferrous chloride), an oxidizing agent and a condensing agent in organic synthesis, as well as a mordant and a hemostatic agent (ferric chloride). An aqueous solution of iron chloride, in particular, an aqueous solution of ferric chloride for etching used to etch lead masks and shadow masks of televisions used as electronic components, or ferrous chloride obtained by reducing ferric chloride The present invention relates to purification of an aqueous solution of iron chloride such as an aqueous solution of iron and an aqueous solution of iron chloride obtained by the purification.

[0002]

2. Description of the Related Art Lead frames as electronic parts and shadow masks for televisions are made of 36 nickel-6.
A so-called invar material such as 4 iron or 42 alloy (iron 58
%, Nickel 42%), 52 alloy (iron 48-50%,
An alloy material such as nickel (50-52%) is manufactured by etching using an aqueous ferric chloride solution.

The aqueous ferric chloride solution used for etching dissolves heavy metals such as nickel in invar and alloy materials by etching, and as the number of etchings increases, heavy metals such as nickel ions enter the solution. It accumulates and the etching ability is reduced.

In particular, when a recent fine and accurate etching process is required, accumulation of heavy metals such as nickel ions in an aqueous ferric chloride solution, and further, reduction of ferric chloride by reduction of ferric chloride. Deterioration of the etching ability due to an increase in ferrous iron is a major problem to be avoided.

[0005] Therefore, by accumulating nickel ions,
Various methods have been proposed for removing and purifying nickel ions in a solution in order to continuously use an aqueous solution of ferric chloride having a reduced etching ability for etching.

For example, JP-A-59-250764 discloses a method in which crystallization is removed as nickel chloride under heat and strong acidity, and JP-A-59-190367 discloses a glyoxime such as dimethylglyoxime. In addition, a method for removing precipitates as nickel glyoxime by the addition of irons, and in JP-A-59-121123, a method for adding and removing massive metallic iron,
JP-A-62-191428, JP-A-3-2535
No. 84, Japanese Unexamined Patent Publication No. 5-85740 and the like propose a method of adding and removing iron powder.

On the other hand, recently, ultra line bars and super invars having excellent thermal expansion resistance have been studied as raw materials for lead frames and shadow masks for televisions.
These ultra line bars and super invars contain cobalt, and cobalt ions are dissolved and accumulated in an aqueous ferric chloride solution which has been subjected to an etching process using these materials.

The concentration of the cobalt ion in the aqueous ferric chloride solution is not so high as that of the nickel ion because the concentration of the cobalt ion is low in terms of lowering the etching ability of the aqueous ferric chloride solution. As described above, ferric chloride is widely used in various applications, and therefore, in applications to be used, the presence of cobalt ions poses a serious problem.

In particular, in an aqueous iron chloride solution for magnetic iron oxide, the existence of cobalt ions is disliked, and not only the cobalt ions in the aqueous ferric chloride solution for etching but also the removal of the cobalt ions from the aqueous iron chloride solution in various applications. Depending on the application, the allowable amount of these ions is 50 ppm or less for nickel ions,
pm or less, and the content of cobalt ions is 20 ppm or less, even 10 ppm or less.

[0010]

SUMMARY OF THE INVENTION The present inventors have found that cobalt ions in an aqueous solution of iron chloride, in particular, an aqueous solution of ferric chloride which is an etching waste liquid used for etching, or ferrous chloride which is a reduced product thereof. The removal of cobalt ions in the aqueous solution was performed using iron powder as in the case of nickel, but the cobalt ions in the ferric chloride aqueous solution could be almost completely removed by adding iron powder alone. Did not.

Therefore, it was examined whether or not cobalt ions could be removed by various methods including a method using iron powder. By adding metallic iron to an aqueous solution of iron chloride in the presence of nickel ions, it was possible to precipitate cobalt ions. And made one proposal earlier.

The nickel ion combination method proposed by the inventors can deposit cobalt ions efficiently, but when the strict tolerance of cobalt ions as described above is imposed, the nickel ion And the amount of iron powder also increased, and could not always be said to be optimal.

For this reason, the present inventors have further studied a method for removing various metal ions including cobalt ions in an aqueous iron chloride solution. As a result, the metal ions such as cobalt ions and nickel ions in the aqueous iron chloride solution are The present inventors have found that they react with sulfides, particularly hydrogen sulfide and ammonium sulfide, and form a precipitate in a solution in an acidic region, so that they can be removed, thereby completing the present invention.

According to the present invention, there is provided an aqueous iron chloride solution capable of removing various metal ions, such as cobalt ions and nickel ions, which have been increased in an aqueous solution by an etching treatment or the like, by simple and easy means, based on the above knowledge, and regenerating the aqueous solution. It is an object of the present invention to provide a method of purifying iron and an aqueous solution of iron chloride having a high etching ability obtained by the method of purification.

[0015]

According to a first aspect of the present invention, there is provided a method for removing metal ions in a solution using a sulfide under an acidic region. This is a method for purifying an aqueous solution of iron chloride.

According to a second aspect of the present invention, there is provided a method for purifying an aqueous solution of iron chloride, comprising removing metal ions in a solution using a sulfide and metallic iron in an acidic region. is there.

In the invention according to claim 5 of the present invention, after adding metal iron to the solution to adjust the pH and partially depositing metal ions, sulfide is added and the metal ions are left. This is a method for purifying an aqueous solution of iron chloride, which comprises removing metal ions.

[0018] The invention according to claim 8 of the present invention is an aqueous solution of iron chloride characterized by being purified by the method for purifying an aqueous solution of iron chloride.

Further, the invention according to claim 9 of the present invention is an aqueous iron chloride solution characterized in that the concentration of cobalt ions obtained by purifying an etching waste liquid containing cobalt ions as impurities is 20 ppm or less. .

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for purifying an aqueous solution of iron chloride and an aqueous solution of iron chloride according to the present invention will be described more specifically.

Iron chloride aqueous solution The aqueous iron chloride solution purified in the present invention contains various metal ions such as cobalt ions and nickel ions as impurities, and it is desired to precipitate and remove various metal ions such as cobalt ions and nickel ions. If
Any iron chloride aqueous solution, that is, an aqueous solution of ferrous chloride or an aqueous solution of ferric chloride may be used, but an etching waste liquid mainly used for an etching process of a lead frame as an electronic component or a shadow mask of a television. The present invention can be favorably applied to the purification of an aqueous ferric chloride solution and an aqueous ferrous chloride solution as a reduced product thereof.

Since ferric chloride in the aqueous ferric chloride solution is easily reduced to ferrous chloride, when the method of depositing metal ions with iron powder in the present invention is adopted, Since ferric chloride has been changed to ferrous chloride, the precipitation of metal ions in the aqueous ferric chloride solution, which is an etching waste liquid, that is, the purification of the aqueous ferric chloride solution, It is carried out through substantially the same reaction as the precipitation of metal ions in the ferrous solution.

Therefore, as described later, even when the ferric chloride aqueous solution is purified by the present invention, the ferric chloride in the solution is changed to ferrous chloride to remove ions, and In order to obtain a ferric chloride aqueous solution which is purified to a certain degree, it is necessary to oxidize (chlorinate) ferrous chloride with chlorine to obtain ferric chloride.

The cobalt ions and may remove metal ions in aqueous solution of iron chloride, but no particular limitation on the amount of other metal ions, for example, the ultra-Invar and Super Invar, the chloride is etched with etching liquid waste Usually, 1000 to 2000 ppm of cobalt ions and about 10000 ppm of nickel ions are present in the aqueous solution of ferrous iron, so that these amounts of cobalt ions and nickel ions, and further, several hundred ppm and several thousand ppm of cobalt ions Can be easily removed according to the present invention.

The sulfide used for the precipitation and removal of sulfide metal ions is not particularly limited as long as it forms sulfide ions in an aqueous solution of iron chloride, particularly an aqueous solution of iron chloride having a pH of 1 or more. Specific compounds that can be applied to the present invention include hydrogen sulfide, ammonium sulfide, and alkali metal sulfides such as sodium sulfide, potassium sulfide, and sodium hydrogen sulfide; and alkali compounds such as magnesium sulfide and barium sulfide. Earth metal sulfides and the like.

Among these compounds, preferred are hydrogen sulfide and ammonium sulfide, which are superior in the ability to precipitate cobalt ions and nickel ions in an aqueous solution of iron chloride. There is no restriction on the use, and industrial hydrogen sulfide can be used without any problem. Further, barium sulfide is also preferably used because barium ion after used for precipitation of nickel ions and cobalt ions can be easily precipitated as barium sulfate with sulfuric acid.

The amount of the sulfide used for the precipitation and removal of metal ions varies depending on the type and amount of metal ions such as nickel ions, which are present as impurities, including cobalt ions in the aqueous iron chloride solution. Although it is necessary to confirm, regarding hydrogen sulfide, in a 5 L-scale test conducted by the inventors, adding 50 to 200 ml / min of hydrogen sulfide at a pressure of 0.2 MPa to an aqueous iron chloride solution causes a problem of metal ions. It was possible to remove to the amount without.

[0028] In precipitation the invention by metallic iron, when depositing a metal ion by hydrogen sulfide, particularly when there are nickel ions, the precipitation of metal ions, as in the conventional, first, may be carried out in metallic iron When nickel ions and cobalt ions coexist, a part of cobalt ions is precipitated together with nickel ions, which is a preferable method.

Further, as will be described later, metallic iron functions not only for the precipitation of metal ions but also as a pH adjuster for the aqueous solution of iron chloride when the metal ions in the aqueous solution of iron chloride are precipitated by hydrogen sulfide. In addition, it has a function of accelerating the precipitation of nickel ions and cobalt ions by being used in combination with sulfides. Therefore, it is preferable to use metal iron in combination. It is also effective in reducing surplus and unnecessary sulfide ions which remain inside.

When depositing cobalt ions with metallic iron in the presence of nickel ions, since the deposition rate of nickel ions is higher than the deposition rate of cobalt ions, it is desirable that the amount of nickel ions be larger than the existing amount of cobalt ions. For example, if the cobalt ion is 200-2000p
In the case of about pm, it is preferable that about 10,000 ppm coexist, and specifically, it is obtained from the target concentration of cobalt ion, deposition time and the like.

When adding nickel ions to the aqueous solution of iron chloride for the precipitation of cobalt ions, it is sufficient to simply add a nickel salt. However, when ferric chloride is present in the aqueous solution of iron chloride, nickel May be added,
Since metallic nickel reacts with ferric chloride to produce nickel ions, it can be used for depositing cobalt ions.

When depositing cobalt ions using nickel ions, even if nickel ions coexist more than cobalt ions, the deposition rate of nickel ions is high. In some cases, the precipitation of cobalt ions may be almost stopped, so if further precipitation of cobalt ions is desired, nickel ions are added and added.
By further adding metallic iron as needed, cobalt ions can be precipitated until the desired amount (concentration) is reduced.

[0033] deposition of metallic iron cobalt ions, as metallic iron when used in combination metallic iron, conventionally, those used for the precipitation of nickel ions are used in the same manner, iron bulk, reduced from iron iron powder Iron powder such as is preferred. Further, in the present invention, not only pure iron but also iron oxide is inferior in nickel removing ion ability as metal iron, but can be partially substituted as metal iron.

The iron powder has a specific surface area of 0.1 to 7 m ^2.
/ G is preferable, and the particle size is preferably 100 mesh or more, and more preferably 150 to
By using such iron powder having a size in the range of 350 mesh, nickel ions and coexisting cobalt ions can be precipitated at an appropriate rate.

The amount of metallic iron to be added may be determined in consideration of the concentration of nickel ions and cobalt ions, the deposition rate, and the like.
The equivalent is not less than 3 equivalents, preferably 3 to 7 equivalents, and if it is less than 1 equivalent, the precipitation of metal ions is insufficient, and if it is 7 equivalents or more, it does not contribute to the precipitation. Since it is eliminated by filtration, it is not preferable in terms of cost and resources.

Precipitation conditions The aqueous solution of iron chloride used to deposit metal ions is p
It is preferably an aqueous solution in an acidic region of H1.5 to 4.5, and most effectively precipitates cobalt ions and other heavy metal ions, for example, nickel ions, from an aqueous solution of iron chloride in the acidic region in this range. Can be.

In order to adjust the pH of the aqueous solution of iron chloride to a range of 1.5 to 4.5, a common alkali hydroxide such as caustic soda may be used. It is preferable to use metallic iron.

The metal ions may be deposited under a nitrogen atmosphere or an air atmosphere.
C., but the preferred temperature range is 40-40.
0 ° C.

As for the deposition time, the deposition temperature is set to 60 ° C.
In this case, the time is preferably at least 1 hour, usually 2 to 10 hours in terms of management.

Since metal ions, including cobalt ions, precipitate as sulfides, they can be separated from the solution by filtering them, and when metal ions are separated and removed using metallic iron, etc. Even if ferric chloride is ferric chloride, since ferric chloride is reduced to ferrous chloride, chlorine is blown into the liquid and chlorinated (oxidized) to ferric chloride. The solution is returned to the above-mentioned condition, and is used as a purified ferric chloride solution, which is used again for etching and the like.

[0041]

The cobalt ion existing as an impurity in the iron chloride solution can hardly be removed by a method conventionally used for removing nickel ion as the same impurity, for example, by adding iron powder alone. By adding sulfides, especially hydrogen sulfide, sulfides, which were considered not to form a precipitate in an acidic state, are formed despite the fact that an aqueous solution of iron chloride is acidic. A specific action enabling removal is achieved.

Further, according to the present invention, other metal ions such as nickel ions are also removed at the same time, and the purification of an iron chloride solution containing various metal ions including cobalt ions as impurities can be performed very easily.

[0043]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to embodiments.

Example 1 Using a 5 L container, a reagent, CoCl ₂ .6H ₂ O, was added to an industrial 35% ferrous chloride solution so that the cobalt ion concentration was about 800 ppm, and the test solution was treated with ferrous chloride. The iron solution was prepared. After adjusting the pH of the test solution to 4.0 with a 20% aqueous sodium hydroxide solution, hydrogen sulfide gas was blown at a flow rate of 110 ml / min with stirring at a temperature of 60 ° C., and reacted for 60 minutes. During the reaction, adjust the pH of the test solution to 20%
It was maintained at 4.0 with aqueous sodium hydroxide solution. 30 after the start of the reaction
After the reaction and the completion of the reaction, a small amount of the test liquid was collected and subjected to solid-liquid separation using filter paper. When the cobalt ion concentration on the liquid side was analyzed, it was 247 ppm after 30 minutes and 1.2 pp after completion.
m.

Example 2 A reagent, CoCl ₂ .6H ₂ O, was added to an industrial 35% ferrous chloride solution so that the cobalt ion concentration became about 800 ppm. Further, iron powder and a small amount of water were added, and pH was adjusted. A test ferrous chloride solution having a pH of 4.0 was prepared. Set the temperature of the test solution to 60
C. and while stirring, supply hydrogen sulfide gas at a flow rate of 110
The reaction was carried out for 120 minutes by blowing at a rate of ml / min. After the completion of the reaction, the pH was 1.5. After 60 minutes from the start of the reaction and after the end of the reaction, a small amount of the test liquid was separated and subjected to solid-liquid separation using filter paper. When the cobalt ion concentration on the liquid side was analyzed,
It decreased to 1.7 ppm after 60 minutes and 1.6 ppm after completion.

Example 3 A reagent, CoCl ₂ .6H ₂ O, was added to an industrial 35% ferrous chloride solution so that the cobalt ion concentration was about 100 ppm.
Was added, and iron powder was further added to the concentration shown in Table 1 to prepare a test ferrous chloride solution. While maintaining the temperature of the test solution at 70 ° C. and stirring, the hydrogen sulfide gas was 0.2 MPa,
The mixture was blown at a flow rate of 30 ml / min and reacted for 60 minutes.
After the reaction, the cobalt ion concentration and the sulfur concentration were analyzed, and the results are shown in Table 1.

[0047]

[Table 1]

[0048] Example 4 Industrial 35% ferrous chloride solution, NiCl reagent _2.6
H ₂ O and CoCl ₂ .6H ₂ O were added, and the nickel ion concentration was about 10,000 ppm and the cobalt ion concentration was about 16
The test ferrous chloride solution was adjusted to be 00 ppm. The test solution temperature was set to 70 ° C., and 3 equivalents of iron powder (average particle size 150 mesh on, specific surface area 0.16 m ² /
g) was added in three portions (at the start, after 2 hours and after 4 hours), and the mixture was reacted for 480 minutes. Hydrogen sulfide gas was blown into this reaction solution at a flow rate of 0.2 MPa and a flow rate of 100 ml / min for 1 hour, and the change in the concentration of nickel, cobalt, iron and sulfide ions in the solution was measured. Table 2 shows the measured results.

[0049]

[Table 2]

Example 5 A reagent, NiCl ₂ .6, was added to an industrial 35% ferrous chloride solution.
H ₂ O and CoCl ₂ .6H ₂ O were added to adjust the test ferrous chloride solution so that the nickel ion concentration and the cobalt ion concentration were each about 50 ppm. After adjusting the pH to 2.5 by adding iron powder to the test liquid, the test liquid was divided into two parts, and one of the test liquids was filtered to remove the iron powder. The temperature of both test liquids was set to 70 ° C., and an aqueous solution of ammonium sulfide (sulfur content: 6%) was added at a concentration of 50 ppm. The concentrations of nickel, cobalt and sulfide ions in the test solution and changes in pH were measured. Table 3 (when iron powder was not filtered) and Table 4 (when iron powder was filtered)
Shown in

[0051]

[Table 3]

[0052]

[Table 4]

Example 6 The reagent NiCl ₂ .6 was added to an industrial 35% ferrous chloride solution.
H ₂ O and CoCl ₂ .6H ₂ O were added to adjust the test ferrous chloride solution so that the nickel ion concentration and the cobalt ion concentration became about 50 ppm, respectively. The temperature of the test solution was adjusted to 60 ° C., and iron powder was charged, followed by stirring until the pH reached 2.5 or more. Next, 3 equivalents of barium sulfide (white powder) were added to nickel and cobalt, and the mixture was stirred and reacted for 4 hours. Changes in the concentrations of nickel, cobalt, sulfide ions and barium ions in the test solution were measured. Table 5 shows the measurement results. Barium ions can be removed by adding sulfuric acid.

[0054]

[Table 5]

Comparative Example 1 The reagent CoCl ₂ .6 was added to an industrial 35% ferrous chloride solution.
By adding H ₂ O, the concentration of cobalt ions is about 1600p
The test ferrous chloride solution was adjusted to pm. The adjusted solution was set at a temperature of 70 ° C., and while stirring, 36 equivalents of iron powder (average particle size: 150 mesh on, specific surface area: 0.16 m ² / g) were added to cobalt three times (at the start, 2
After 4 hours, the mixture was added in portions, and the change in the cobalt ion concentration was measured. Table 6 shows the measurement results.

Comparative Example 2 The reagent NiCl ₂ .6 was added to an industrial 35% ferrous chloride solution.
H ₂ O and CoCl ₂ .6H ₂ O were added, and the nickel ion concentration was about 10,000 ppm and the cobalt ion concentration was about 16
The test ferrous chloride solution was adjusted to be 00 ppm. The solution temperature was set to 70 ° C., and while stirring, 5 equivalents of iron powder (average particle size: 150 mesh on, specific surface area: 0.16 m ² /
g) was added in three portions (at the start, after 2 hours and after 4 hours), and the change in nickel and cobalt ion concentrations was measured. Table 6 shows the measurement results.

[0057]

[Table 6]

As is clear from the results of Examples and Comparative Examples, the removal of cobalt ions from the iron chloride solution was substantially as follows.
It is hardly possible with metallic iron, and only by adding sulfides, especially hydrogen sulfide, can cobalt ions be removed effectively and nickel ions can be removed at the same time.

As proposed by the present inventors,
When nickel ions coexist, it is possible to remove cobalt ions by adding iron powder.However, in order to reduce the amount of cobalt ions, the deposition rate is high and the concentration decreases rapidly. It is necessary to add nickel ions or add iron powder.
It is not always possible to say.

When removing cobalt ions,
If nickel ions are also present in the iron chloride solution,
As described above, the addition of metallic iron causes the precipitation of cobalt ions together with the nickel ions. Thus, the combined use of metallic iron and hydrogen sulfide enables more effective removal and precipitation of cobalt ions and nickel ions.

Further, iron metal not only functions to precipitate metal ions but also functions as a pH adjuster for the aqueous iron chloride solution when the metal ions in the aqueous iron chloride solution are precipitated by hydrogen sulfide. It has the function of accelerating the precipitation of nickel ions and cobalt ions by being used together with the sulfides, and also reduces excess and unnecessary sulfide ions remaining in the sulfide-added aqueous iron chloride solution. .

[0062]

According to the method for purifying an aqueous solution of iron chloride of the present invention, cobalt ions and heavy metal ions contained in an aqueous solution of ferric chloride or its waste liquid whose etching ability has been reduced by the etching process of the ultra line bar or super invar. Can be effectively removed, and the ferric chloride aqueous solution can be used again as an etching solution, thereby exhibiting an excellent effect in resource saving.

The aqueous iron chloride solution of the present invention can be easily obtained from an aqueous solution of ferric chloride having a reduced etching ability or a waste liquid thereof, and exhibits an excellent effect on resource saving in that it can be reused. Is what you do.

Claims (9)

[Claims] 1. A method for purifying an aqueous solution of iron chloride, comprising removing metal ions in a solution using a sulfide under an acidic region. 2. A method for purifying an aqueous solution of iron chloride, comprising removing metal ions in a solution using a sulfide and metallic iron in an acidic region. 3. The method according to claim 1, wherein the metal ions to be removed are nickel or cobalt ions. 4. The method for purifying an aqueous solution of iron chloride according to claim 1, wherein the acidic region has a pH in the range of 1.5 to 4.5. 5. An iron chloride which is characterized by adding metallic iron to a solution to adjust the pH and partially depositing metal ions, and then adding sulfide to remove remaining metal ions. A method for purifying an aqueous solution. 6. The method according to claim 5, wherein the sulfide is hydrogen sulfide, ammonium sulfide, or barium sulfide. 7. The iron chloride aqueous solution is an etching waste liquid.
The method for purifying an aqueous iron chloride solution according to any one of the above. 8. An aqueous iron chloride solution purified by the method for purifying an aqueous iron chloride solution according to claim 1. 9. An aqueous iron chloride solution obtained by purifying an etching waste liquid containing cobalt ions as impurities and having a cobalt ion concentration of 20 ppm or less.