JPS582272B2 - Electrolysis method of chlorine compound corrosive solution - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an electrolytic method for a chlorine compound corrosive solution, and particularly to an electrolytic method for recovering corroded copper as metallic copper from the corrosive solution that has corroded copper such as printed circuit boards. .

In this type of electrolysis method, chlorine gas is generated from the anode during electrolysis.

This chlorine gas is highly toxic, and it is necessary to suppress the generation of chlorine gas as much as possible from the viewpoint of preventing pollution and replenishing the chlorine compound corrosive solution with chlorine.

Conventional electrolytic methods for suppressing the generation of chlorine gas include methods for adjusting the electrolytic voltage, methods for lowering the corrosive liquid temperature,
Diaphragm methods and the like are known.

The first method is to change the electrolysis voltage to the normal electrolysis voltage of 4.5 to 5V.
Electrolysis is performed at a lower voltage of about 2V to suppress the generation of chlorine gas.

The second method is to lower the temperature of the etchant to about 25° before electrolysis, conduct electrolysis with this low-temperature etchant to suppress the generation of chlorine gas, and raise the temperature of the etchant to about 45° after copper recovery. It is used for corrosion of copper.

The third method is to arrange a diaphragm in the electrolytic cell and supply a corrosive solution to the cathode side to suppress the generation of chlorine.

However, in any of the above methods, chlorine gas is inevitably generated even if attempts are made to suppress the generation of chlorine gas, so the generated chlorine gas is led to a neutralization tower, where it is neutralized with a chemical solution. must be released into the atmosphere.

Furthermore, the first method lowers the electrolysis voltage to about 2V, which is lower than the voltage of 4.5 to 5V that provides the best electrolysis efficiency, and therefore has the disadvantage that the electrolysis efficiency is extremely reduced.

In addition, in the second method, in order to lower the temperature of the electrolyte,
The disadvantage is that the reaction rate of electrolysis is slow and that a refrigerator is required to cool the corrosive liquid before electrolysis and a heater is required to heat the corrosive liquid after electrolysis.

The third method has the disadvantage that the structure of the electrolytic cell becomes complicated because the diaphragm is disposed in the electrolytic cell.

The present invention aims to provide an electrolytic method that improves the above-mentioned drawbacks of the prior art.

In view of the shortcomings of the conventional technology, which attempts to suppress the generation of chlorine gas as much as possible, the present inventor actively carried out electrolysis using an electrolytic tank with a sealed anode chamber, and removed the chlorine gas generated in the anode chamber and the metal. The recovered corrosive liquid is introduced into a sealed absorption tank, where the chlorine gas is forcibly absorbed into the corrosive liquid. It is characterized in that it is recycled by returning it to the anode chamber of the tank, and that the gas pressure in the anode chamber and the absorption tank can be maintained within predetermined limits.

below. A specific example of the method for electrolyzing a chlorine compound corrosive solution according to the present invention will be described with reference to the accompanying drawings.

The accompanying drawing is a flow sheet diagram showing one embodiment of the electrolysis method of the present invention.

In the figure, 1 is a storage tank that stores a corrosive solution containing a large amount of copper that corrodes printed circuit boards and the like.

Reference numeral 2 designates an electrolytic cell having a completely sealed anode chamber 23, and is provided with an outlet 21 on the cathode side for recovering the deposited copper and an outlet 22 for discharging the corrosive solution that has recovered the copper.

Reference numeral 3 denotes a completely sealed absorption tank, in which a blow-off pipe 31 and a nozzle 32 are arranged at the bottom and the top, a filler 33 is placed between the blow-off pipe 31 and the nozzle 32, and a chlorine gas is placed in the lower part. An overflow chamber 34 is provided in which the corrosive liquid that has absorbed gas is discharged by overflow.

Reference numeral 4 denotes a pressure regulating tank that keeps the gas pressure in the electrolytic cell 2 and absorption tank 3 constant, and a float 4 that contains a chemical solution for neutralizing chlorine gas in the lower part and floats and sinks in the chemical solution to adjust the gas pressure.
1 is floated, a nozzle 42 is provided at the top, and a filler 43 is provided between the nozzle 42, the float 41, and the chemical solution.

5 is a hydrochloric acid tank, 6 is a mixing tank, and 7 is a regeneration storage tank.

The storage tank 1 and the electrolytic tank 2, the outlet 22 of the electrolytic tank 2 and the lower part of the absorption tank 3, the bottom of the absorption tank 3 and the nozzle 32, the overflow chamber 34 of the absorption tank 3 and the mixing tank 6, and the mixing tank 6 Corrosive liquid flow pipes 81 and 8 are provided between the storage tank 7 and the regeneration storage tank 7, respectively.
2, 83, 84 and 85, and a chlorine gas flow pipe 86 is connected to the anode chamber 23 of the electrolytic cell 2, the blow-off pipe 31 of the absorption cell 3, and the majority of the absorption cell 3 and the anode chamber 23 of the electrolytic cell 2, respectively.
.
2, and a hydrochloric acid feed pipe 80 is connected between the hydrochloric acid tank 5 and the mixing tank 6.

In addition, pumps 91, 92, 93,
94 and 95 are provided, and an electromagnetic valve 96 is provided in the middle of the hydrochloric acid feed pipe 80 for feeding an amount of hydrochloric acid corresponding to the shortage of chlorine in the corrosive liquid from the absorption tank 3.

Next, the electrolysis method of the present invention using the above-mentioned plant will be explained.

A corrosive solution containing a large amount of copper by corroding printed circuit boards and the like in the storage tank 1 is fed to the electrolytic tank 2 by a pump 91, and electrolysis is performed in the electrolytic tank 2.

As a result, copper is deposited on the cathode and collected from the outlet 21, and the corrosive solution with the copper thus collected is discharged from the outlet 21.
2 to the lower part of the absorption tank 3.

On the other hand, chlorine gas is generated on the anode side due to the electrolysis, but since the anode chamber 23 is sealed, the chlorine gas is not dissipated into the atmosphere and is blown from the anode chamber 23 to the absorption tank 3 by the pump 94. 32.

Since the absorption tank 3 is of a closed type as described above, the chlorine gas blown out from the blow-off pipe 32 is primarily absorbed into the corrosive liquid stored in the lower part of the absorption tank 3, and then the pump 92 and the corrosive liquid flow path. The chlorine gas that is secondarily absorbed into the corrosive liquid sprayed and circulated through the pipe 83 and nozzle 32 and is not absorbed is returned from the majority of the absorption tank 3 to the anode chamber 23 of the electrolytic tank 2 via the chlorine gas flow pipe 87. The chlorine gas is then recycled.

On the other hand, the corrosive liquid that has absorbed chlorine gas is sent from the overflow chamber 34 of the absorption tank 3 to the mixing tank 6 via the flow pipe 84, the shortage of chlorine in the corrosive liquid is measured, and the amount of chlorine is adjusted accordingly. The amount of hydrochloric acid is transferred from the hydrochloric acid tank 5 to the feed pipe 80 and the solenoid valve 96.
The corrosive liquid and hydrochloric acid are mixed in the mixing tank 6 to regenerate the corrosive liquid, and the regenerated corrosive liquid is sent to the regeneration storage tank 7 by the pump 93. .

The inside of the anode chamber 23 of the electrolytic cell 2 and the inside of the absorption tank 3 are sealed as described above, but these are communicated with the inside of the float 41 of the pressure regulating tank 4 through the chlorine gas flow pipes 87 and 88. Therefore, when the gas pressure in the anode chamber 23 of the electrolytic cell 2 and the absorption tank 3 increases or decreases,
The float 41 of the pressure regulating tank 4 floats and sinks above the chemical solution, thereby maintaining the gas pressure in the anode chamber 23 of the electrolytic tank 2 and the absorption tank 3 within predetermined limits.

In addition, since the chemical solution in the pressure adjustment tank 4 is circulated through the feed pipe 89, the nozzle 42, and the tank 4 by the pump 95, the gas pressure in the anode chamber 23 of the electrolytic tank 2 and the absorption tank 3 should When the float 41 rises above the chemical liquid surface and chlorine gas is ejected outside the float 41, the ejected chlorine gas is neutralized by the chemical liquid circulating in the pressure regulating tank as described above. can be released into the atmosphere.

As described above, the present invention conducts electrolysis by introducing a chlorine compound corrosive solution containing metals through corrosion into an electrolytic tank with a sealed anode chamber, and recovers chlorine gas and metals generated in the anode chamber by the electrolysis. The corrosive liquid is introduced into a sealed absorption tank.
Chlorine gas is forcibly absorbed into the corrosive liquid in the absorption tank. Nevertheless, the chlorine gas that could not be absorbed into the corrosive solution is recycled by returning it to the sealed anode chamber of the electrolytic cell, and the sealed anode chamber and the sealed absorption tank of the electrolytic cell are further recycled. It is connected via a gas flow pipe to a float suspended above the liquid level in the pressure regulating tank, and the float floats up and down to maintain the gas pressure in the anode chamber and absorption tank of the electrolytic tank within a predetermined limit. Compared to conventional methods of suppressing the generation of chlorine gas, electrolysis can be actively carried out with good electrolysis efficiency, and the chlorine gas generated by electrolysis is not neutralized and discharged unnecessarily. ，
Since this is actively absorbed into the corrosive solution in the absorption tank, the amount of injection of hydrochloric acid, etc. to make up for the lack of chlorine in the corrosive solution is much smaller than in the conventional technology. Even though the anode chamber and absorption tank of the electrolytic cell are sealed, the float in the pressure regulating tank maintains the gas pressure in the anode chamber and absorption tank within a predetermined limit to perform electrolysis extremely safely and efficiently. It has the effect of

[Brief explanation of the drawing]

The accompanying drawing is a flow sheet diagram showing one embodiment of the method for electrolyzing a chlorine compound corrosive solution according to the present invention.

Claims (1)

[Scope of Claims] 1. A corrosive solution in which a chlorine compound corrosive solution containing metal due to corrosion is introduced into an electrolytic tank with a sealed anode chamber, and chlorine gas and metals generated in the anode chamber are recovered by the electrolysis. is introduced into a sealed absorption tank, and the chlorine gas is forcibly absorbed into the corrosive solution in the absorption tank. The electrolytic cell is returned to the anode chamber for recycling, and the sealed anode chamber and the sealed absorption tank of the electrolytic cell are connected via a chlorine gas flow pipe to a float suspended above the liquid level of the pressure regulating tank. 1. A method for electrolyzing a chlorine compound corrosive solution, characterized in that the gas pressure in an anode chamber and an absorption tank of an electrolytic cell is maintained within a predetermined limit by floating and sinking a float. 2 A neutralizing chemical solution for chlorine gas is stored in the lower part of the pressure regulating tank, the float is floated on top of the neutralizing chemical solution, and the neutralizing chemical solution is delivered to a nozzle provided at the upper part of the pressure regulating tank via a pump. 6 Spray to circulate the neutralizing chemical solution in the pressure adjustment tank, and in the event that the float rises above the chemical surface and chlorine gas spews out, the chlorine gas will be neutralized and released into the atmosphere. A method for electrolyzing a chlorine compound corrosive solution according to claim 1.