JP2010059502A - Treatment method and device for copper etching waste solution - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To refine away sulfuric acid so as to achieve reutilization, further, to eliminate the exhaust of a waste solution and to improve treatment efficiency. <P>SOLUTION: The treatment method for a copper etching waste solution is characterized in that hydrogen peroxide in a copper etching waste solution comprising copper sulfate, hydrogen peroxide and sulfuric acid is decomposed away in an oxygen peroxide separator 1, thereafter, water and sulfuric acid are refined and separated by a pressure dialyzer 2, further, copper sulfate is concentrated, and next, copper ions in the concentrated copper sulfate solution are recovered as metal copper by an electro-winning apparatus 3. In the electro-winning, the concentration of copper sulfate is preferably controlled to 30 to 60 g/L. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a technique for recovering sulfuric acid and copper from a copper etching waste liquid containing copper sulfate, hydrogen peroxide and sulfuric acid, and treating the waste liquid.

  Although copper etching is performed in order to remove unnecessary copper foil in the manufacturing process of the printed wiring board, copper is dissolved in the etching solution as copper sulfate by the etching process, and when the concentration is increased, the ability of the etching solution is reduced. Therefore, it is necessary to replace the etching solution or remove copper in the etching solution.

Conventionally, an electrolytic method has been proposed as a method for recovering metallic copper from a copper etching waste solution. For example, Japanese Patent Application Laid-Open No. 2003-13274 uses a barrel electrolysis apparatus, Japanese Patent Application Laid-Open No. 2003-73878 uses an electrolytic cell equipped with a diaphragm, and Japanese Patent Application Laid-Open No. 2005-187865 uses an electrode material and voltage. In other words, two-stage electrolysis is performed.
JP2003-13274 JP 2003-73878 A JP 2005-187865 A

  The above conventional technique is intended to recover metallic copper, and cannot recover sulfuric acid. Further, since the entire amount of waste liquid is electrolyzed, the power consumption is large and the time required for the treatment is also long.

  An object of the present invention is to purify and separate sulfuric acid so that it can be reused, to eliminate waste liquid discharge, and to improve processing efficiency.

The method for treating a copper etching waste liquid according to the present invention is a method of decomposing and removing hydrogen peroxide in a copper etching waste liquid containing copper sulfate, hydrogen peroxide and sulfuric acid, and then purifying and separating water and sulfuric acid by a pressure dialysis method. Then, the copper ions in the concentrated copper sulfate solution are recovered as metallic copper by an electrolytic collection method.
In the electrolytic collection, the concentration of copper sulfate is preferably about 30 to 60 g / L (liter). Moreover, a barrel electrolytic cell can also be used for the cathode which deposits metallic copper besides a copper plate.
Subsequent to the above step, the copper recovery can be further improved by re-concentrating the electrolytic solution having a reduced copper ion concentration by pressure dialysis.
The decomposition of the hydrogen peroxide is preferably performed by AC electrolysis with low power consumption, but can be performed by heat treatment or other known methods. Moreover, it is preferable to perform pressure dialysis with the apparatus provided with the spiral charged membrane.
The invention according to claim 5 is an apparatus for carrying out the present invention, and is for separating oxygen peroxide in an electrolytic cell or the like for decomposing and removing hydrogen peroxide in a copper etching waste solution containing copper sulfate, hydrogen peroxide and sulfuric acid. Apparatus, pressure dialysis apparatus for purifying and separating water and sulfuric acid from waste liquid from which hydrogen peroxide has been removed and concentrating copper sulfate, and electrowinning apparatus for collecting copper ions in the concentrated copper sulfate solution as metallic copper If necessary, the electrowinning device and the pressure dialysis device are connected by a pipe, and the waste liquid whose copper ion concentration is reduced by removing most of the copper metal by the electrowinning device can be concentrated again by the pressure dialysis device. Configure as follows.

In the present invention, since water and sulfuric acid are separated by pressure dialysis of the waste liquid from which hydrogen peroxide has been removed, the water and sulfuric acid can be returned to the etching solution and reused. And since these are separated and electrowinning is performed only for the waste liquid having a high copper ion concentration, copper can be collected under optimum conditions by keeping the copper ions and sulfate ions at a certain appropriate concentration. .
That is, according to the present invention, recovery and reuse of sulfuric acid can be achieved, metallic copper can be efficiently collected, and waste liquid can be prevented from being discharged.

FIG. 1 shows an example of an apparatus for carrying out the present invention. The treatment liquid from which hydrogen peroxide has been separated and removed by the oxygen peroxide separation apparatus 1 in the copper etching waste liquid is supplied to the pressure dialysis apparatus 2. In the pressure dialysis apparatus 2, the treatment liquid is concentrated and supplied to the electrowinning apparatus 3, and the separated water and sulfuric acid are recovered and reused.
In the electrowinning device 3, metallic copper is deposited on the cathode. The concentrated solution on which the metallic copper is deposited is supplied again to the pressure dialysis apparatus.
Examples of the present invention will be described below.

  1 L of etching waste liquid containing 5% sulfuric acid, 3% hydrogen peroxide, and 25 g / L of copper was heat-treated with the oxygen peroxide separator 1 to separate and remove hydrogen peroxide. This treatment solution was applied to the pressure dialysis machine 2 and concentrated about twice to obtain 500 mL of a copper sulfate solution containing 50 g / L of copper. This copper concentrate was introduced into an electrowinning device 3 composed of an insoluble anode and a cathode made of a copper plate and operated at a current density of 2 A / dm 2 for 5 to 5 hours to obtain 10 g of metallic copper on the cathode plate. Moreover, 500 mL of separated water containing sulfuric acid obtained by the pressure dialysis apparatus 2 was recovered and reused.

An etching waste liquid 1 L containing 5% sulfuric acid, 3% hydrogen peroxide, and 25 g / L of copper was subjected to alternating current electrolysis using the oxygen peroxide separator 1 to separate and remove hydrogen peroxide. The electrolysis was carried out at a frequency of 50 Hz and an effective current density of 5 A / dm 2 for 8 hours to decompose and remove hydrogen peroxide to 1/100 or less.
Thereafter, the treated solution was subjected to pressure dialysis in the same manner as in Example 1 and concentrated about twice, and this copper concentrate was electrolyzed in an electrowinning apparatus at a current density of 2 A / dm 2 for 5.5 hours. 10 g was obtained.
Next, the treatment liquid from which the metallic copper was separated was supplied again to the pressure dialysis apparatus 2 and pressure dialysis was performed to obtain 300 mL of a copper sulfate solution containing 50 g / L of copper. This copper sulfate solution was electrolyzed under the same conditions as above to obtain 6 g of copper.
By repeating pressure dialysis and electrolysis of the treatment solution twice, 90% or more of metallic copper could be recovered.

Comparative example

An etching waste liquid 1L containing 5% sulfuric acid, 3% hydrogen peroxide, and 25 g / L of copper was subjected to AC electrolysis using the oxygen peroxide separation apparatus 1 under the same conditions as in Example 2 to separate and remove hydrogen peroxide.
Thereafter, this treatment solution was not concentrated but electrolyzed as it was in an electrowinning device, and metallic copper was deposited on the cathode plate. With the progress of electrolysis, the copper ion concentration decreased. When the copper ion concentration was several g / L or less, the current density had to be reduced to half or less because of the limit current density reduction. Further, the copper metal deposited on the cathode plate was rough and easily formed into protrusions, and it was impossible to continue operation for a long time. In order to eliminate the decrease in the copper ion concentration, it may be possible to re-concentrate the copper ion by distillation. However, since the sulfuric acid concentration increases due to poor economic efficiency, it cannot be completely recovered and is not realistic.
As described above, when the electrolytic treatment is performed without concentrating the treatment liquid, the treatment must be stopped in a state where the copper ion concentration in the waste liquid is still high in order to drain. In order to drain into the sewage together with the general waste water of the factory, it is necessary to make it 0.01 g / l or less. Therefore, in order to drain the above waste liquid into the sewage, the copper ions are separated in advance by precipitation aggregation or the like. Needed.

  According to the present invention, the recovery and reuse of sulfuric acid in the copper etching waste liquid can be achieved, the metallic copper can be efficiently collected, and the waste liquid can be prevented from being discharged. It is what is done.

It is the schematic of the apparatus of this invention

Explanation of symbols

1 Oxygen peroxide separation device 2 Pressure dialysis device 3 Electrolytic collection device

Claims (5)

After decomposing and removing hydrogen peroxide in the copper etching waste liquid containing copper sulfate, hydrogen peroxide and sulfuric acid, water and sulfuric acid are purified and separated by pressure dialysis, and the copper sulfate is concentrated, and then the concentrated copper sulfate solution A method for treating a copper etching waste liquid, characterized in that copper ions are recovered as metallic copper by electrolytic collection A method for treating a copper etching waste liquid, comprising reconcentrating an electrolytic solution having a reduced copper ion concentration by pressure dialysis after the step of claim 1 The method for treating a copper etching waste liquid according to claim 1 or 2, wherein the decomposition of hydrogen peroxide is performed by alternating current electrolysis. The method for treating a copper etching waste liquid according to claim 1 or 2, wherein the pressure dialysis is performed by an apparatus including a spiral charged membrane. An oxygen peroxide separation device for decomposing and removing hydrogen peroxide in copper etching waste liquid containing copper sulfate, hydrogen peroxide and sulfuric acid, and purifying and separating water and sulfuric acid from the waste liquid from which hydrogen peroxide has been removed and sulfuric acid A copper etching waste liquid treatment apparatus comprising: a pressure dialysis apparatus for concentrating copper; and an electrowinning apparatus for collecting copper ions in the concentrated copper sulfate solution as metallic copper.

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