JPS60238195A - Treatment of high concentration copper-containing waste solution - Google Patents

Abstract

PURPOSE:To perform the quantitatively and qualitatively excellent treatment of a copper waste solution, by forming a slurry by using an alkali neutralizing agent having a good dehydration property and dehydrating said slurry at specific pH while precipitating leaked copper in the dehydration separated solution as metal copper. CONSTITUTION:The copper waste solution from a printed circuit board manufacturing industry is stored in a neutralization tank at first and a neutralizing agent having a good dehydration property such as calcium hydroxide is added to said waste solution under stirring and the pH of the waste solution is held to 6.2-7. The formed slurry is subjected to solid-liquid separation in a dehydrator 3 to obtain a dehydrated sludge cake (b). The dehydration separated solution (a) is sent to a redox tank 4 where an iron powder (d) is thrown into said separated solution while pH is adjusted to 3-4 and redox reaction is performed to precipitate the leaked copper ion as metal copper. By this method, quantitatively and qulitatively excellent treatment is performed without diluting the copper waste solution.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention treats a heavy metal-containing waste liquid, particularly a mixed liquid containing a large amount of copper, such as an etching waste liquid related to electronic parts, by a neutralization method and an iron powder oxidation-reduction method.

This invention relates to improvement of a method for treating wastewater containing high concentration steel. For example, in industries such as the printed circuit board manufacturing industry and the precision plating industry, waste liquid containing a high concentration of copper (hereinafter referred to as copper waste liquid) is discharged, and the copper concentration can reach tens of thousands of ppm. Ammonium persulfate, hydrogen peroxide, etc. are commonly used in the printed circuit board manufacturing industry, and it has been difficult to treat these copper waste liquids with conventional liquid IT, but these can be neutralized and iron powder redox. Dealing with the law will solve the following problems.

Conventional treatment methods include incineration or discharge by electrolysis and dilution. Incineration has high running costs and may also cause secondary pollution such as air pollution. The discharge of water through electrolysis and dilution deviates from the original purpose of treatment, which is detoxification.

In other words, conventional treatment methods cannot satisfy the technical requirements of recovering copper and rendering waste liquid harmless, unless some complicated and costly methods are excluded.

The present invention solves the drawbacks of the conventional treatment methods as described above.The purpose of the present invention is to be able to treat copper waste liquid without reducing its concentration by diluting it, and to achieve qualitatively and quantitatively superior treatment capacity. An object of the present invention is to provide a method for treating copper waste liquid that can exhibit the following properties.

The technical configuration of the present invention that achieves this objective is as follows: A. A neutralizing agent is added to copper waste liquid generated from printed circuit board etching, etc. to generate a neutralized product, which is separated into solid and liquid, and each is disposed of or recycled. In the method for treating copper waste liquid comprising the steps of utilizing B, an alkaline neutralizing agent with good dehydration properties is used as a neutralizing agent to create a neutralized slurry.

C9 The neutralized slurry was dehydrated at pH 6.2 to 7.0, leaked into the dehydrated separation solution (1 eak), and oxidized with iron powder while adjusting the pH with acid to Fipn 3 to 4 for copper ions. A reduction reaction is performed to precipitate metal.

The present invention relates to a method for treating copper waste liquid consisting of the above A to D.

It goes without saying that the above-mentioned copper waste liquid refers to the waste liquid itself generated from etching of printed circuit boards, precision plating, etc., but it is not limited to a single waste liquid, but can be treated by a mixed system of two or more types of copper waste liquid. Including cases where it is a target. Rather, a mixed waste liquid of two or more of these seven types of copper waste liquid may be more suitable for the treatment target of the present invention. In other words, in the printed circuit board manufacturing industry, etc., it is costly to separate various types of copper waste liquid according to the amount used, so mixed copper waste liquid is often produced. This is because it is difficult to transport the materials and there is a high possibility that they will be mixed together.

(Neutralizing agent) Since the present invention is an improvement of the neutralization method, it is the same as the conventional neutralization method in that it includes a pH adjustment step of neutralizing the waste liquid with an alkali. It must be in good condition. Preferably, calcium hydroxide or a material containing calcium hydroxide as a main component is preferred.

(Neutralization range) One feature of the present invention is that the pH is set to 6.2 to 7.0. It is difficult to precipitate all the copper using only the neutralization method. The pH is set at 6.2 to 7.0 in order to keep the concentration of copper ions leaking into the dehydrated liquid within a certain range in order to reduce the processing cost in combination with the iron powder oxidation-reduction method (Figure 1).

If the pH is adjusted to below 6.2 or above 7.0, leakage will occur. Since the copper ion concentration becomes high, a large amount of iron powder and pH adjusting acid are consumed in the iron powder redox method. In addition, these phenomena require a long time in the subsequent solid-liquid separation step, and a large amount of sludge is produced, resulting in high maintenance costs. Particularly in acidic pH ranges, when reusing dehydrated sludge cake, hydrogen ions will have a negative effect on the furnace.

As can be understood from the above explanation, the present invention takes advantage of the fact that the pH of the neutralized slurry can be easily adjusted.
Neutralization and dehydration are carried out within the range of 7.0, thereby intentionally controlling the concentration of copper ions leaking into the dehydrated separated liquid.

(Iron powder oxidation-reduction method) Copper ions leaked into the dehydrated separated liquid are treated with sulfuric acid to pH 3~
4 and mix the iron powder according to the copper concentration to perform the oxidation-reduction reaction.

Note that when the pH is adjusted with hydrochloric acid, the reactivity is good, but there is a risk that copper will be redissolved, so sulfuric acid is preferably used. The reason why the pH is adjusted to 3 to 4 in the iron powder redox method is as follows: If the pH is below 3, an oxidized coating will form on the surface of the iron powder and the substitution reaction will be hindered. . Therefore, the reaction does not occur even with an appropriate amount of iron powder, and a large amount of iron powder must be consumed.
l/-1teFe (OH) 3m nH2 over H4
O070 is precipitated and SS increases. Also, due to the acid concentration being too high, iron powder may not be dissolved. As a result of the above, solid-liquid separation after pH 3 or lower or pH 4 or higher becomes extremely difficult, resulting in increased running costs. An example of a processing method using the BAK of this invention is 70-sheets (
The explanation will be based on Fig. 2). Copper waste liquid is first transferred to neutralization tank 1.
Add a neutralizing agent to this and adjust the pH to 6 while stirring.
．． 2-7. After that, solid-liquid separation is performed through slurry [2] and dehydration@3, and a dehydrated sludge cake is discharged. The dehydrated separated liquid is converted into acid 1 and sent to reducing species 4. If a high-pressure dehydrator (for example, a tube press dehydrator) is used in the solid-liquid separation process, it can be carried out at about 100 kf/c++l, so the moisture content of the dehydrated sludge cake is extremely low, which is advantageous in terms of reusing the dehydrated sludge cake. In other words, relatively low pressure (4
ks/cyd~tOkp/d) When using a dehydrator, the moisture content is high, and if it is to be reused, a drying process is added after dehydration, and storage equipment is required, which increases costs. The dehydration separation liquid component is mainly composed of leaked copper ions, and the pH is adjusted to 3 to 4 in the oxidation-reduction tank 4, and iron powder is introduced to perform the oxidation-reduction reaction. After precipitation of metal steel, solid-liquid separation is carried out in the primary separator 5. do. 6 is the primary filter, 7 is the primary pH adjustment tank. 0 Dehydrated separated liquid containing no substances other than heavy metals #-t1st p
The pH is adjusted to 10 to 10.5 using an HX cypress 9 to form iron hydroxide flocs, and the flocs are grown in a coagulation tank 8 and solid-liquid separated in a secondary separator 9.

At this time, heavy metals other than iron are also co-precipitated with iron hydroxide = 10 is a secondary filter. 11 is a secondary pH adjustment tank.

The present invention will be specifically explained below with reference to Examples.

[Example 1] Appropriate amounts of copper waste solutions A, B, and C companies (discharge business Wr) having the composition shown in Attached Table 1 were stored in a neutralization tank, and carbide slag (Ca (OH)2) was added to adjust the pH to 6.5 K (2 hours).

Next, this was put into a dehydrator via a slurry tank and separated into a dehydrated sludge cake and a dehydrated separated liquid.

The pH in the slurry tank is 6.6, the total filtration capacity of the dehydrator is 1,
Automatic filter press with 62 m/
Filtration pressure 4Ky/al, compression pressure Kql ad,
Arata with 10 c c/aim sec (200
/l filtration time 18 minutes, squeezing time 2 minutes).

The moisture content of this dehydrated sludge cage is 50”%.
When a content test was conducted, it was about Cu7v/W. The dehydrated separated liquid contained Cu3501R9/l.

While adjusting the pH to 3 to 4 with sulfuric acid, 0.35 to 0.4 Kql d of iron powder was further added to carry out the redox reaction (for 1 hour). After the metal steel was deposited, it was sent to a primary separation device. The Cu concentration of the separated liquid component that passed through the primary filter was 3.3/l, which means that this separated liquid complied with ocean dumping regulations. This separated liquid is reused in the primary p
The pH was adjusted to 10.5 in the Hll1 adjustment tank to generate iron hydroxide flocs, and after spm of flocculant was injected in the flocculation tank, the flocs were sent to a secondary separation device. At this time, the treated liquid components obtained without passing through the secondary filter were as follows. This means that it complies with sewer discharge regulations.

Concentration; Cd<0.01. S-Mn<Q, 5. Pb<0.
1S-Fe Q,7, Cu0621, F2
．． 0. Zn <0.5T-Cr <Q, Q5, n
- Amount of hexane extracted substance: Undetected BOD/20, Iodine consumption: 100 [Unit: 11] [Example 2] (Comparative data) Copper waste liquid companies A, B, and C (discharging business) with the composition shown in Attached Table 2
Prepare an appropriate amount of 9♂ and add 1.5 of carbide slag to this.
About wt was mixed and stirred and neutralized to pH 7.8. The pH in the slurry tank is 8.0, and the moisture content of the dehydrated sludge cake in the filter press dehydrator is 50%.
]. In addition, Cu Id2,0OO in the dehydrated separated liquid
It was 9/l in 11.

Attached Table 2 [Unit: ■/l] In other words, at this stage there is too much Cu, and the amount of iron powder required for the redox reaction is 1.8 to 1.9 Kql d Te simultaneous t/c
It can be seen that the amount of sulfuric acid for pH adjustment is also a factor in increasing the sycocost. If water treatment is intended at this stage, it is clear that not only will the amount of alkali consumed in the primary pH-adjusting cypress be large, but also the amount of sludge in the solid-liquid separation pressure will increase, increasing maintenance costs.

Even if the neutralization pH is 6.2 or lower, the same result will not occur, but when the dehydrated sludge cake is reused as copper, the furnace pressure hydrogen ions will have an adverse effect. In addition, in copper waste liquid containing heavy metals other than copper, these heavy metals leak into the dehydrated separated liquid, making it difficult to treat the dehydrated separated liquid such as the aforementioned ocean dumping treatment or sewage discharge treatment.

As per SM-Example 2 above), the dewatered sludge cake obtained by the treatment method of the present invention can be reused as copper. In order to lower the moisture content, use a high pressure dehydrator (10
When using 0Kqlal), the water content is 3s~4.
Experimental results have been obtained in which a dehydrated sludge cake of about 0'5/-1 can be obtained.

In addition to the above-mentioned industries, in the industrial waste treatment industry,
more complete, thorough and safe ocean dumping or water treatment;
Reuse is desirable. According to the present invention, even when a large amount of ammonia coexists with heavy metals in the copper waste solution, it is removed within the set neutralization slurry pH value range, and in water treatment, it is virtually completely removed by co-precipitation with iron hydroxide. Detoxification will be achieved.

[Brief explanation of drawings]

Figure 1 is a graph showing an example of the correlation between the pH of the #image-grading waste liquid slurry (neutralized slurry 17-) and the copper concentration in the dehydrated separation liquid in the present invention, and Figure 2 is a graph of the method for treating copper waste liquid according to the present invention. This is a flow sheet showing an example.

Claims (1)

[Scope of Claims] 1) Adding a neutralizing agent to high-concentration copper-containing waste liquid generated from the printed circuit board manufacturing industry, precision plating industry, etc. to produce a neutralized product, which is separated into solid and liquid and reused. A method for treating high-concentration steel-containing waste liquid, which consists of the process of treating waste liquid, etc. - An alkaline neutralizing agent with good dehydration properties is used as the neutralizing agent, and the neutralized slurry is dehydrated at a pH of 6.2 to 7.0. do. While adjusting the copper ions #'1 pHa to 4 leaked into the dehydrated separated liquid with acid (hereinafter referred to as pHM acid regulation), an oxidation/reduction reaction using iron powder (hereinafter referred to as iron powder oxidation-reduction method) is carried out. ) and depositing it as metallic steel. Method for treating waste liquid containing high concentration steel 2) Claims in which the alkali neutralizing agent is calcium hydroxide or a substance containing calcium hydroxide as a main component. No. 13! To the high-temperature, high-temperature cooking before discontinuation of the HIF! 3) The high temperature according to claim 1, in which the pH-adjusting acid is sulfuric acid, hydrochloric acid, or one containing these as a main component. 4) The method for treating a high concentration steel-containing waste liquid according to claim 1, wherein the high concentration steel-containing waste liquid is used alone, and for some trout, a mixed waste liquid is used.