JPS6034501B2 - How to recover iron chloride - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for recovering iron chloride.

More specifically, the present invention relates to a method for recovering iron chloride in which steel is separated from a waste iron chloride aqueous solution used for copper etching and ferric chloride is recovered as ferrous chloride.
．． In addition to water, the waste iron chloride aqueous solution used for copper etching generally contains 10 to 20% (by weight, hereinafter referred to as the same) of ferrous chloride (FeC12) and 7 to 1% of ferrous chloride (FeC12).
It contains 5% ferric chloride (FeCl3), 7-13% cupric chloride (CuC12), and a small amount of free hydrochloric acid, and from the viewpoint of pollution problems and resource conservation, it is preferable to remove iron from such industrial waste liquids. Although there is a strong desire to develop an efficient method for removing or recovering components and components, no effective method has yet been found.

In view of the current situation, the present inventors have conducted intensive studies to efficiently recover iron chloride from a waste iron chloride aqueous solution used for copper etching, and have found that it is possible to add iron to a waste iron chloride aqueous solution having the above composition. According to the following reaction, [11 CuC120Fe→ FeC120C
u↓ and eC120Fe→ are reduced and precipitated and separated from eCI steel, and ferric chloride is recovered as ferrous chloride. Eventually, the iron component is converted into ferrous chloride and the copper component is converted into metal steel. At the same time, we found scales that could be effectively recovered.

However, when the redox reaction with iron is carried out at a rate that is usually industrially satisfactory,
If the reaction is carried out at a temperature of A problem arose in that it became impossible to do so (using iron plates required removing copper adhesion from the iron surface with a hammer, making the operation complicated).

In order to eliminate such obstacles, the present inventors further investigated various reaction conditions, and found that by carrying out this reaction at a relatively low temperature range, which is considered unfavorable in terms of reaction rate, a completely unpredictable result was achieved. As a result, the copper that precipitates hardly covers the surface of the iron, and even if a small amount of copper does adhere to the surface of the iron, it is in the form of adsorption, and it is difficult to continue the reaction. Ensure that there are no problems and that the reaction is carried out at a temperature of 40-5000 and p.
The present inventors have discovered that if the reaction is carried out under the conditions of H2-4, the reaction rate does not slow down so much despite the reduction in reaction temperature, and the reaction can proceed smoothly, leading to the completion of the present invention.

That is, in the present invention, iron is added to a waste iron chloride aqueous solution used for copper etching, and the reaction temperature is 40 to 6yo and the pH is
The present invention relates to a method for recovering iron chloride, the gist of which is to carry out a reaction under conditions 2 to 4, separate copper from the produced copper and ferrous chloride, and scale the ferrous chloride.

According to the method of the present invention, iron components are recovered as ferrous chloride from the waste iron chloride aqueous solution used for copper etching, and can be reused as a raw material for producing ferric chloride for knot etching. Similarly, etched copper can be efficiently recovered with high purity.

In the method of the present invention, iron is added to a waste iron chloride aqueous solution used for copper etching under conditions of a reaction temperature of 40 to 65°C, preferably 40 to 50 oo, and a pH of 2 to 4. Although the object of the present invention is achieved, the reaction temperature is usually room temperature or higher.

When the reaction temperature is higher than 6,500 ℃, the surface of the deposited copper is coated as if it were plated, which is not preferable because it is not effectively utilized for the reaction. 4000
When it is lower than , the reaction time becomes too long, which is not preferable.

When the pH of the aqueous solution is less than 2, the reaction rate generally becomes slow, which tends to be unfavorable from an industrial standpoint. Note that the pH of the waste iron chloride aqueous solution having the above composition will not rise above 4, but if the pH rises above 4 due to the progress of the reaction, ferrous chloride will turn into ferric hydroxide, which will interfere with the reaction. , the pH of the reaction system should be maintained within the above range by adding hydrochloric acid.

The form of the iron used in the present invention is not limited in any way, and any form such as powder, rod, or plate may be used as appropriate, but the iron may progress more quickly and smoothly. For this purpose, it is advantageous to use a form with a large surface area, such as a powder.

Further, the amount of iron used is the amount required to react with cupric chloride and ferric chloride in the waste iron chloride aqueous solution used for copper etching, or more than that amount. When the amount of iron used is less than the above range, cupric chloride is not completely oxidized to copper and cannot be removed, and ferric chloride cannot be reduced to ferrous chloride, which is not preferable. Incidentally, the excess iron remaining without being consumed in the reaction is repeatedly used for the reaction treatment of the waste iron chloride aqueous solution. Therefore, the ferrous chloride and metallic steel obtained by the method of the present invention can be separated and easily recovered from the waste iron chloride aqueous solution consisting of the above composition, but the recovered ferrous chloride 1-iron is usually obtained in an aqueous solution concentration of 30-40%, while metallic copper can be separated and recovered in extremely high purity. The present invention will be specifically explained below with reference to Examples and Comparative Examples.
The present invention is not limited to such embodiments.

Example 1 The following liquid composition was used as an inexpensive iron chloride aqueous solution (hereinafter referred to as steel etching waste liquid) used for copper etching.

1 Pour copper etching waste liquid LK9 and iron plate (material: carbon steel, 3.0 skin x 1.1 arc x 0.3 arc, total surface area 180 cm) into a round bottom flask, and add 50 ml of copper etching waste while worshiping the lights.
oo for 24 hours. The surface of the iron plate used in this reaction was in such a state that the deposited copper slightly adhered and was adsorbed.

Next, new copper etching waste liquid was treated in the same manner as described above, except that this iron plate (the iron plate used once for the reaction) was continuously used again.

The cupric chloride and ferric chloride components in the resulting treatment solution were treated to the same result as the previous treatment, and the reused iron plate did not pose any hindrance to the reaction. Furthermore, new copper etching waste liquid was treated in the same manner as above, except that the iron plate that had been used twice in this reaction was used again and again.

The ferric chloride and ferric chloride components in the resulting treatment solution were treated to the same result as the previous time, and the iron plate used two times in succession reacted in the same way as the iron plate used the first time. It was not a hindrance. The surface of the iron plate used for this reaction three times in succession was in a state in which a small amount of the deposited copper was adsorbed, and there was no problem even when it was used for the reaction four more times in a row.

The analysis results of each component in the treated solution were analyzed in the first
Shown in the table. Table 1 As is clear from Table 1, in the method of the present invention, the surface of the iron plate used is not coated with deposited copper and can be used continuously without any problems. Moreover, the cupric chloride component in the copper etching waste liquid can be easily removed with good results, which is extremely advantageous in terms of waste water treatment.

Comparative Example 1 In a round waist flask, copper etching waste liquid (same as that used in Example 1) LK9 and iron plate (same material, dimensions and surface area as used in Example 1, new iron plate that will not be reused) Prepared 155 evenings, 80 qo from Kashiazusa Shina
The reaction was carried out for 24 hours.

The surface of the iron plate used in this reaction was coated with deposited copper in a plating-like state. Next, new copper etching waste liquid was treated in the same manner as described above, except that this iron plate (the iron plate used once for the reaction) was continuously used again. The cupric chloride and ferric chloride components in the resulting treatment solution could not be treated to the same extent as the previous treatment, and the surface of the reused iron plate was coated with copper, so it was not effective for the reaction. I couldn't survive. ”Furthermore, except that the same iron plate used twice in this reaction was used again and again,
Fresh copper etching waste liquid was treated in the same manner as above.

The cupric chloride and ferric chloride components in the resulting treatment solution are difficult to further process, and the former in particular can hardly be removed, and the iron plate used twice in succession is no longer effective for deodorization. It was unusable. The surface of the iron plate used for this reaction three times in succession was in a state as if it had been plated with deposited copper, and was completely coated with copper.

Table 2 shows the analysis results of each component in these treatment solutions.
Table 2 As is clear from Table 2, when the reaction temperature is high, the cupric chloride and ferric chloride components in the copper etching waste solution cannot be effectively converted to steel and ferrous chloride, respectively.
Moreover, the iron plate could not be used continuously for the reaction.

Examples 2 to 3 As Example 2, 1 kg of copper etching waste solution (same as that used in Example 1) was placed in a round bottom flask.
A steel plate (made of the same material and size as those used in Example 1) of 77 mm (total surface area: 90 mm) was charged, and reacted at 5,000 mm for 24 hours while shaking.

Each component in the treatment solution thus obtained was analyzed and quantified. In addition, as Example 3, the reaction was carried out in the same manner as in Example 2, except that a 450 mm iron plate (same material and size as used in Example 1) (total surface area 516) was used, and the treatment solution was quantified. did.

The analysis results are shown in Table 3 together with those of each component in the treatment liquid obtained by the first reaction in Example 1.
Table 3 It is clear from Table 3 that in the method of the present invention, very good results can be obtained by using a larger amount of iron plates or by using iron plates with a larger surface area.

Further, in all Examples, the copper that was precipitated and separated was of high purity (containing about 1% iron as an impurity).

Comparative Examples 2 to 3 As Comparative Examples 2 and 3, the reaction temperature was changed from 5000 to 20
The reaction was carried out in the same manner as in Example 1 and Example 2, except that the same iron plate was used, except that the reaction was carried out using the same iron plate.

Each component in the obtained treatment liquid was analyzed and quantified. The results are shown in Table 4. The surface of the iron plate used was not coated with deposited copper.

Table 4 Note that in Comparative Example 2, it took 96 hours to bring the CuC12 concentration to 1 oppm, the same as in Example 1.

As described above, in the method of the present invention, copper can be separated from the waste iron chloride aqueous solution used for copper etching, and ferric chloride can be easily recovered as ferrous chloride, which is extremely advantageous industrially. It is.

Claims (1)

[Claims] 1. Iron is added to the iron chloride aqueous solution used for copper etching and reacted at a temperature of 40 to 65°C, and the copper is separated from the produced copper and ferrous chloride to produce ferrous chloride. A method for recovering iron chloride, characterized by obtaining the following: 2. The method for recovering iron chloride according to claim 1, wherein the reaction is carried out at a temperature of 40 to 50°C. 3. The method for recovering iron chloride according to claim 1 or 2, wherein the reaction is carried out at a pH in the range of 2 to 4.