JP2004238683A - Method for treating copper-etching waste liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for recovering copper from a copper-etching waste liquid containing sulfuric acid, hydrogen peroxide and a hydrogen peroxide stabilizer, without producing sludge, wasting electricity, considering variations in current efficiency caused by variations in a composition of copper and hydrogen peroxide, and causing an increase of the cost. <P>SOLUTION: The method for treating the copper-etching waste liquid comprises heating the copper-etching waste liquid containing sulfuric acid, hydrogen peroxide and a hydrogen peroxide stabilizer containing an organic compound, to 60 to 80°C, keeping the liquid in the same temperature range for 0.5 to 10 hours to decompose hydrogen peroxide, and then recovering a copper content as metallic copper through electrolysis. The treatment method further comprises, prior to the electrolysis, mixing a copper separation-treated waste liquid from which the copper content has been already recovered as metallic copper, with the copper-etching waste liquid to decrease COD, and then electrolyzing the resultant liquid to recover copper with high purity. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for treating a copper etching waste liquid containing a hydrogen peroxide stabilizer comprising sulfuric acid, hydrogen peroxide and an organic compound. More specifically, copper etching containing a deteriorated etchant, that is, a hydrogen peroxide stabilizer composed of sulfuric acid, hydrogen peroxide, and an organic compound, is used for dissolving unnecessary portions of copper foil in a manufacturing process of a multilayer printed wiring board. The present invention relates to a method for treating waste liquid.
[0002]
[Prior art]
In a manufacturing process of a multilayer printed wiring board, a so-called copper-clad substrate having a copper foil on a surface is used. Etching containing a hydrogen peroxide stabilizer consisting of sulfuric acid, hydrogen peroxide, and an organic compound to remove unnecessary portions to form a desired circuit on the copper foil or roughen the surface to improve adhesion. A solution is used, but the etching solution gradually increases the copper concentration and decreases the performance.
[0003]
When the copper concentration exceeds a predetermined value, the etching ability is reduced and the continuation of the processing becomes inappropriate, so that the etching solution is replaced with a new etching solution. At that time, the deteriorated etching solution is discharged as an etching waste solution, and has been conventionally collected and disposed of as industrial waste by a specialized waste solution processing company. The waste liquid contains a high concentration of hydrogen peroxide in addition to copper, and also contains various harmful compounds such as organic compounds added for suppressing the self-decomposition of hydrogen peroxide.
[0004]
For this reason, it is impossible to dispose of this waste in rivers and the like only by neutralization treatment, because various harmful compounds are discharged to rivers and the like, and it is not possible due to laws and regulations concerning wastewater treatment. . For this reason, various harmful substances such as copper containing a large amount of multiple chemicals have been settled and separated, and the sludge generated has been disposed of in landfills. Was.
[0005]
In the above treatment of the etching waste liquid, copper becomes sludge, so it will be mixed with other harmful substances such as hydrogen peroxide and a hydrogen peroxide stabilizer, but a method of separating and recovering copper as a single compound is also available. It has already been proposed (JP-A-6-49665). This method is to utilize the difference in solubility with temperature of copper sulfate, separating the copper as crystals CuSO 4 · _5H 2 _O.
[0006]
In this method, when the copper concentration becomes high, the copper sulfate is easily crystallized, and therefore, during the crystallization treatment, the copper sulfate crystal blocks the piping attached to the crystallization apparatus, and the problem that the handling becomes difficult. is there. In addition, although hydrogen peroxide remains in the mother liquor after copper sulfate separation, an organic compound as a hydrogen peroxide stabilizer also remains in the mother liquor, and the hydrogen peroxide remaining in the mother liquor can be easily removed. Is difficult to disassemble.
[0007]
In order to solve these problems, the present inventors have recently developed a method of electrolyzing the etching waste liquid to decompose hydrogen peroxide and recovering copper as metallic copper, and have already applied for a patent (Japanese Patent Application 2001). 196621). In this method, as described above, the decomposition of hydrogen peroxide and the recovery of metallic copper can be performed in one process called electrolysis, but the decomposition of hydrogen peroxide at the cathode occurs before the deposition of copper, Since the precipitation of copper occurs later, the current efficiency of copper deposition is extremely reduced.
[0008]
In addition, there are the following problems.
That is, when the concentration of hydrogen peroxide in the etching waste liquid is particularly high, for example, 15 g / L or more, once deposited copper is redissolved, and when copper is selected as the cathode material, the copper of the cathode material is not dissolved. It is dissolved and disappears, or the cathode plate falls off, which causes inconvenience in actual operation and equipment design.
[0009]
The present inventor has already successfully developed a method for electrolyzing an etching waste liquid, which has made it possible to avoid a decrease in the current efficiency, and applied for a patent (Japanese Patent Application No. 2001-261620). In this method, the electrolytic chamber is divided into an anode chamber having an anode by a diaphragm and a cathode chamber having a cathode, and an etching waste liquid containing hydrogen peroxide and copper sulfate is supplied to the anode chamber. It supplies an etching waste liquid containing no hydrogen peroxide after electrolysis in the anode chamber.
[0010]
By doing so, the electrolysis of hydrogen peroxide in the anode compartment and the deposition of copper in the cathode compartment can be performed simultaneously, and the current efficiency of copper deposition in the earlier application of the present applicant has been greatly improved. I was able to. As described above, the method of a later application by the present applicant can greatly improve the current efficiency of copper deposition as compared with the method of the prior application developed by the present applicant. It has been found that another problem arises when the waste liquid is treated industrially.
[0011]
The problems are the following (1) to (4), and (1) is as follows.
(1) Since the etching waste liquid is discharged when the deteriorated etching liquid is replaced with a new etching liquid, it is discontinuously and irregularly performed. The concentration of copper and hydrogen peroxide remaining in the waste liquid greatly varies, and therefore, the fluctuation of the current efficiency due to the variation of the composition ratio of the two is large, and the apparatus capacity must be excessively increased.
[0012]
The other (2) to (4) are as follows.
(2) Since the deposited copper falls off from the electrode, it is necessary to frequently clean the electrolytic cell.
(3) Further, when the precipitated copper was dissolved with sulfuric acid, it was found that insoluble components were contained. Therefore, it was low in purity and was unsuitable for dissolution and reuse.
(4) It is impossible to completely suppress the anolyte containing hydrogen peroxide from diffusing and infiltrating into the cathode chamber side where copper is deposited through the diaphragm, and it is impossible to completely avoid the decomposition of hydrogen peroxide in the cathode chamber. Impossible, and a reduction in the electrical efficiency of copper deposition is inevitable.
Further, if the airtightness of the diaphragm is improved in order to suppress the diffusion, the voltage increases, and the power consumption increases.
[0013]
Further investigation of (2) and (3), among these problems, revealed the following facts.
{Circle around (1)} The deposited copper surface is black instead of the clear red color peculiar to copper.
{Circle around (2)} During the electrolysis of the etching waste liquid, components other than copper are also precipitated together with copper, thereby lowering the purity of copper.
{Circle around (3)} The higher the amount of insoluble components contained in copper, the more easily the precipitated copper falls off.
[0014]
The inventor of the present invention has intensively researched and developed to solve these problems. At that time, in order to remove hydrogen peroxide in the copper etching waste liquid before electrolysis in advance, decomposition was attempted using a commercially available hydrogen peroxide decomposing agent (catalase enzyme), but failed. In order to further examine the thermal decomposition of hydrogen peroxide in the copper etching waste liquid, various attempts were made to change the heating temperature, but surprisingly, the temperature was increased to 60 to 80 ° C. and maintained at the same temperature range for a predetermined time. It has been found that it can be decomposed despite the presence of a hydrogen oxide stabilizer.
[0015]
From the above, the prospect of resolving the problems (1) and (4) has been made clear. Based on this finding, the hydrogen peroxide in the copper etching waste liquid was removed in advance, and electrolysis was performed. As a result, electrolysis could be performed smoothly as expected, and the current efficiency and power consumption of copper deposition were further improved as compared with the invention of Japanese Patent Application No. 2001-261620 by the present inventors. However, it was also confirmed that the deposited copper was still desorbed from the electrode and was of low purity, so that the problems (2) and (3) and the facts (1), (2) and (3) could not be solved as expected. did it.
[0016]
Therefore, further studies were made to solve these problems and facts. First, attention was paid to components contained in a copper etching waste liquid that precipitate on the cathode together with copper and reduce the purity of copper. Except for copper, the components contained in this waste liquid are sulfuric acid, hydrogen peroxide and a hydrogen peroxide stabilizer.Hydrogen peroxide is a substance that has been almost completely removed in advance and is formed from hydrogen and oxygen. Therefore, it is unlikely that black matter is produced as a result of the electrolysis.
[0017]
Further, sulfuric acid can be expected to generate gaseous hydrogen at the cathode by electrolysis, but it is unlikely that sulfuric acid will generate a black substance as in the above case. From such a fact, it was speculated that the presence of the hydrogen peroxide stabilizer composed of an organic compound had some influence on the formation of this black substance. From the above, attention was paid to the presence of this organic compound.
[0018]
Although attention was paid to the organic compound constituting the hydrogen peroxide stabilizer in this way, since it is difficult to specify the compound name and the content of the compound contained therein, the total amount of the organic compound contained is first known. I decided to measure COD. As a result, the COD in the etching waste liquid is different for each copper etching waste liquid that is discharged every time a new etching liquid is exchanged, and the value of the value is such that the deposited copper is separated from the electrode and a black substance is formed. In this case, it was found that the amount was about 2000 mg / L or more.
[0019]
Since this COD component is present in a high concentration of sulfuric acid and is dissolved and cannot be removed by solid-liquid separation such as filtration, there is no way to remove it before electrolysis. It was decided to dilute the COD component to reduce the concentration of the later etching waste liquid, and then to perform electrolysis. Since a large amount of sulfuric acid is present in the etching waste liquid at the time of the dilution, sulfuric acid containing no impurities was first used.
[0020]
When the etching waste liquid from which the hydrogen peroxide having a reduced concentration of the COD component diluted with sulfuric acid was removed was electrolyzed in the same manner, it was found that the surface became lighter in black. Therefore, when a plurality of types of COD components having different concentrations were produced from this etching waste liquid and electrolyzed, it was found that the lower the concentration of the COD components, the lighter the black color of the deposited copper surface was. Furthermore, it was also found that the lower the concentration of the COD component, the less the deposited copper was desorbed and the more firmly the copper was fixed to the electrode surface. From these facts, it is expected that the problems of (1), (2), (3) and (4) and the facts of (1), (2) and (3) will be solved.
[0021]
As described above, the problems of (1), (2), (3), and (4) and the facts of (1), (2), and (3) can be solved. A patent application (Japanese Patent Application No. 2003-22717) was filed for this technology immediately before this application. The invention discloses that a copper etching waste solution containing a hydrogen peroxide stabilizer consisting of sulfuric acid, hydrogen peroxide and an organic compound is heated to 60 to 80 ° C. and maintained at the same temperature range for 0.5 to 10 hours to produce hydrogen peroxide. A method for treating a copper etching waste liquid, comprising decomposing and electrolyzing to recover a copper component as metallic copper, wherein an inorganic acid is mixed before electrolysis to reduce COD.
[0022]
Although this technology solves the above-mentioned various problems and is technically excellent, as described above, it uses a new inorganic acid or inorganic salt aqueous solution such as sulfuric acid to reduce the concentration of the COD component. In this regard, this technology has also caused an increase in cost, and the necessity of developing a technology capable of further solving this problem has been felt, and studies have begun. In order to reduce the cost, the possibility of using waste acid instead of using an inorganic acid such as sulfuric acid or an aqueous solution of an inorganic salt as an industrial product was determined.
[0023]
Therefore, when re-focusing on this inorganic acid, since the acid is used to reduce the concentration of the COD component, if the concentration of the COD component is low and the range is such that the precipitation of copper during electrolysis is not hindered. I thought it could be used. Therefore, paying attention to the fact that the copper separation treatment waste liquid after the recovery of the copper component discharged after the electrolytic treatment of the copper etching waste liquid is a waste acid containing sulfuric acid, its COD should be measured just in case. I made it. As a result of the measurement, it was found that the COD after the electrolysis was lower than that before the electrolysis. Therefore, this waste acid was mixed with the copper etching waste liquid after the decomposition of hydrogen peroxide and then electrolyzed.
[0024]
As a result, similarly to the case where an inorganic acid such as sulfuric acid is mixed, the black color of the precipitated copper surface becomes thinner as the mixing amount of the waste acid increases, and the copper desorption is small and firm. It was found that it was fixed to the electrode surface. As described above, the problems (1), (2), and (3) and the problems (1), (2), and (3) also occur when the copper separation treatment waste liquid is used instead of the inorganic acid such as sulfuric acid. The above fact can be resolved.
Further, since the waste acid is used instead of the inorganic acid used for reducing COD, the above-described avoidance of the increase in cost can be achieved.
[0025]
[Problems to be solved by the invention]
Therefore, the present invention solves the problems of the conventional copper etching waste liquid treatment and the problems of the copper etching waste liquid treatment recently proposed by the present inventor, and purifies copper deposited by electrolysis with high purity. It is an object of the present invention to provide a copper etching waste liquid treatment technique that can be recovered by the above method. It should be particularly emphasized that the present invention is to solve the problem of providing a copper etching waste liquid treatment technique that can be performed at a lower cost when recovering copper deposited by electrolysis with high purity. is there.
[0026]
The problems to be solved by the present invention are specifically as follows.
(1) There is no generation of sludge that requires landfill disposal as in the conventional case, and it is possible to reduce a great deal of processing cost associated therewith.
{Circle around (2)} The problem of the technology which can be carried out together with the recovery of copper and the decomposition of hydrogen peroxide in an electrolytic cell recently developed by the present inventor, which is associated with the decomposition of hydrogen peroxide generated at the cathode prior to the deposition of copper. Avoid wasting power,
{Circle around (3)} Further, this technique avoids the problem of the technique of simultaneously performing the deposition of copper and the decomposition of hydrogen peroxide in an electrolytic cell, which is a problem of the technique. What you can do
(4) that copper deposited by electrolysis can be recovered with high purity;
(5) The materials and materials used should be as low cost as possible (reduce costs compared to the electrolytic copper etching waste liquid treatment technology applied for a patent immediately before this application).
[0027]
[Means for Solving the Problems]
A method for treating a copper etching waste liquid, which is a means adopted by the present invention to solve the above-mentioned problem, comprises a step of reducing a copper etching waste liquid containing a hydrogen peroxide stabilizer consisting of sulfuric acid, hydrogen peroxide and an organic compound to 60 to 80 ° C. A method for treating a copper etching waste liquid, comprising heating and maintaining the same temperature range for 0.5 to 10 hours to decompose hydrogen peroxide, and then electrolyzing to recover a copper component as metallic copper. COD is reduced by mixing a copper separation treatment waste liquid after recovering CO as metallic copper.
[0028]
In the present invention, the hydrogen peroxide in the copper etching waste liquid is removed by heating before being introduced into the electrolytic cell, and it is not necessary to remove the hydrogen peroxide by electrolysis in the electrolytic cell. Therefore, in the electrolytic cell, no electric power is consumed for decomposing hydrogen peroxide, so that the amount of electricity generated thereby is not wasted and the current efficiency is high. Further, it is not necessary to consider the fluctuation of the current efficiency due to the fluctuation of the composition ratio of copper and hydrogen peroxide, and it is not necessary to increase the capacity of the apparatus in consideration of the fluctuation.
[0029]
In addition, since the copper separation waste liquid containing sulfuric acid is used instead of sulfuric acid or the like to reduce COD in the copper etching waste liquid, the cost increase accompanying the use of sulfuric acid does not occur, and This also makes it possible to reduce the processing cost associated with the reduction of the sulfuric acid treatment, which is an excellent point to be particularly emphasized in comparison with the invention developed and patented immediately before the present application.
[0030]
In the treatment of the copper etching waste liquid of the present invention, copper is recovered by electrolysis, and copper which causes sludge generation does not remain in the processing waste liquid discharged from the electrolytic tank. Of course, there is no problem of disposal by the processor. Since the treatment waste liquid does not contain copper as described above, it can be released by performing a neutralization treatment, and in some cases, can be used as an acid for neutralizing alkaline wastewater.
[0031]
In the present invention, the reason why the removal of hydrogen peroxide by electrolysis in the electrolytic cell can be avoided is that the decomposition of hydrogen peroxide is achieved by heating the copper etching waste liquid to 60 to 80 ° C. and maintaining the same at the same temperature for a predetermined time. This is based on the fact that the present inventor has found that thermal decomposition can be performed even when a stabilizer that suppresses hydrogen peroxide is contained, whereby hydrogen peroxide can be decomposed and removed in advance.
Further, the reason why the present invention can recover high-purity copper is based on the fact that the present inventors have similarly found that the purity of precipitated copper is improved by diluting the COD component in the copper etching waste liquid. is there.
[0032]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
The method for treating a copper etching waste liquid according to the present invention comprises heating a copper etching waste liquid containing a sulfuric acid, a hydrogen peroxide and a hydrogen peroxide stabilizer composed of an organic compound to 60 to 80 ° C., and keeping the copper etching waste liquid at the same temperature range for 0.5 to 10 hours. A method for treating a copper etching waste liquid in which hydrogen peroxide is maintained and decomposed and then electrolyzed to recover a copper component as metal copper, and copper separation after the copper component is recovered as metal copper before electrolysis. COD is reduced by mixing a processing waste liquid.
[0033]
The copper etching waste liquid to be treated according to the present invention is an etching liquid used for dissolving and removing an unnecessary portion when forming a circuit on a copper foil on a copper-clad board in a manufacturing process of a multilayer printed wiring board, a so-called etching liquid. A typical example is a waste liquid in which the performance of the soft etching liquid has deteriorated. This etching waste liquid contains dissolved copper at a high concentration.
[0034]
The waste liquid naturally contains sulfuric acid and hydrogen peroxide which are components for copper etching, and also contains an organic compound which is a hydrogen peroxide stabilizer for suppressing the decomposition of hydrogen peroxide. I have. The copper etching waste liquid to be treated in the present invention is not limited to the above-mentioned waste liquid in which the performance of the so-called soft etching liquid is deteriorated, but contains copper dissolved by etching, and contains sulfuric acid, hydrogen peroxide and peroxide. Any etching waste liquid containing a hydrogen oxide stabilizer can be used without any particular limitation.
[0035]
In the present invention, the copper etching waste liquid is heated to 60 to 80 ° C. and maintained at the same temperature range for 0.5 to 10 hours to decompose hydrogen peroxide and then electrolyzed, but heated to 60 to 80 ° C. The reason for maintaining the temperature in the same range for a predetermined time is to efficiently decompose hydrogen peroxide by heating. Heating and holding at 60 ° C. or higher is because the lowest temperature at which hydrogen peroxide can be decomposed economically is the same temperature, while heating and holding at 80 ° C. or lower makes it possible to use inexpensive and simple equipment. This is because safety was considered. The concentration of hydrogen peroxide in the waste copper etching solution after thermal decomposition is preferably 2.0 g / L or less. The reason why the concentration of hydrogen peroxide is preferably low is that the current efficiency at the time of the electrolytic treatment is improved.
[0036]
There is no particular limitation on the hydrogen peroxide stabilizer contained in the copper etching waste liquid, and the copper etching waste liquid containing the hydrogen peroxide stabilizer comprising various organic compounds can be treated by the method of the present invention. Examples of the stabilizer include propanol, cyclohexylamine, adipic acid and butyl diglycol. In the present invention, it is possible to appropriately treat a copper etching waste liquid containing one or more of these.
[0037]
In the present invention, it is necessary that the copper etching waste liquid is mixed with the copper separation treatment waste liquid before the electrolysis to reduce COD. It is based on the fact that the present inventors have found that the COD is reduced in the copper separation waste liquid obtained after the electrolysis, and the concentration of the organic compound is reduced by mixing the copper separation waste liquid with the copper etching waste liquid. This is because it has been found that the purity of the precipitated copper is improved when the mixture is electrolyzed as compared with the case where the electrolysis is performed without mixing.
[0038]
This etchant is used continuously as long as the predetermined etching performance is developed, and is discarded when it deteriorates.Hydrogen peroxide is decomposed even though it contains a hydrogen peroxide stabilizer. It is impossible to completely suppress the concentration, and the concentration of the organic compound which is a hydrogen peroxide stabilizer in the etching solution increases with time because the stabilizer is added sequentially.
[0039]
When the etchant does not exhibit the specified ability, the etchant with the deteriorated performance is discarded and replaced with a new etching.However, the COD is measured for the concentration of the organic compound in the discarded etchant. As a result, it was found that there was a substance that was about 2000 mg / L and exceeded in an extreme case. When this waste liquid was electrolyzed as it is in a barrel electrolytic bath, it was also found that copper in the etching waste liquid was deposited on the copper pipe stored in the barrel, but was soon removed and the copper pipe hardly grew.
[0040]
Also, a black film is formed on the surface of the copper pipe, and a large number of flake-like copper pieces that have fallen off from the pipe accumulate in the electrolytic cell. It was also found that the copper purity was low. As mentioned above, since it is hard to imagine a means for removing COD before electrolysis, it was found that copper pipes grew when the etching waste liquid was diluted three times with sulfuric acid and electrolysis was performed, and the handling became easy. Was. It was also found that the surface had a red color unique to copper and was of high purity. The COD at that time was about 600 mg / L.
[0041]
Therefore, the relationship between COD and the deposited copper was further examined. When electrolysis was carried out in a barrel electrolytic tank at about 1500 mg / L, copper was deposited without being detached from the copper pipe as the electrode, and the surface was not removed. Is also thin, and when the concentration is 1000 mg / L or less, the precipitated copper is firmly fixed to the copper pipe. As a result, it was found that flakes did not occur, and that the surface had a red color peculiar to copper.
[0042]
From this fact, it has been found that COD is effective as a criterion for determining whether high-purity, easy-to-handle copper can be deposited. Further, as described above, it has been found that the COD is preferably 1500 mg / L or less, and more preferably 1000 mg / L or less during the etching waste liquid electrolysis. These facts have been found when developing the copper etching waste liquid treatment technology, which was filed immediately before the present application.
[0043]
In the technology filed immediately before this application, an inorganic acid such as sulfuric acid or an aqueous solution of an inorganic salt is used for diluting the waste liquid, and it has been desired to reduce the cost increase accompanying this use. From such a fact, as described above, attention was paid to the fact that the copper separation treatment waste liquid after the recovery of the copper component discharged after the electrolytic treatment of the copper etching waste liquid was waste acid containing sulfuric acid, and its COD was measured. It was found that the COD was lower than before the electrolysis. Specifically, the COD before the electrolysis was 1920 mg / L, but was 1028 mg / L after the electrolysis.
[0044]
Further, when this copper separation waste liquid was mixed with copper etching waste liquid and electrolyzed instead of sulfuric acid used in the technology applied for patent immediately before the present application, as described above, surprisingly, an inorganic acid such as sulfuric acid was mixed. Similarly to the case, it was also found that the black color of the deposited copper surface became thinner as the mixing amount of the waste acid was increased, and that the copper was hardly detached and was firmly fixed to the electrode surface.
[0045]
From these facts, also in the present invention, the COD in the etching waste liquid during electrolysis is preferably 1500 mg / L or less, and more preferably 1000 mg / L or less. The lower the COD, the higher the quality of high-purity copper. In addition, when the waste liquid is diluted, copper is also diluted in the same manner as the organic compound. Therefore, it is also understood that a change in the copper concentration is a measure of a change in the COD component.
[0046]
Next, embodiments of the present invention will be described in more detail with reference to the drawings.
FIG. 1 illustrates a basic configuration of an apparatus for treating a copper etching waste liquid according to the present invention. The apparatus shown in this figure has a simple structure including a heating apparatus 1, a heat retaining tank 2 and an electrolytic tank 3, and a copper etching waste liquid is first supplied to the heating apparatus 1 and heated to 60 to 80 ° C. At this time, heating is performed in several to ten and several times, and the waste liquid is stored in the heat retaining tank 2 after heating.
[0047]
The copper etching waste liquid stored in the heat retention tank 2 is maintained at the above-mentioned temperature, hydrogen peroxide is thermally decomposed, and then introduced into the electrolytic tank 3. Here, a part of the copper separation treatment waste liquid after the copper was deposited by the previous electrolysis was left in the electrolytic cell 3 and mixed with this waste liquid to dilute the copper and COD components and the like. Later, it is electrolyzed to deposit metallic copper, and copper is recovered. Note that the recovery of copper by this apparatus is performed in a batch process.
[0048]
There is no particular limitation on the heating device 1, the heat retaining tank 2 and the electrolytic bath 3 in this device, and various devices can be used as long as they have the respective functions. The heating device is preferably provided with a device for heating the copper etching waste liquid in a container.Examples of the heating device include various types of corrosion-resistant heaters and heat exchangers, and a quartz tube heater is preferable in terms of low cost and corrosion resistance. .
[0049]
In addition, in a heating device provided with a heating device in this container, it is preferable to stir the liquid in the device, and for this purpose, it is preferable to take out a part of the liquid and circulate it. In addition, the heating of the copper etching waste liquid and the maintenance of the heating temperature can be performed only by the heating device 1. As described above, since the heating performance of the heating device can be reduced to a small capacity by installing the heat insulation tank 2 and heating and heat insulation separately, the heat insulation tank 3 is installed. Is desirable.
[0050]
As for the heat retaining tank, various containers can be used without particular limitation as long as the copper etching waste liquid heated to 60 to 80 ° C. by the heating device can be maintained in the temperature range. What covered the container with various heat insulating materials can be used preferably. Note that the internal volume of the heat retaining tank 2 needs to be several times or more that of the heating device 1. Further, it is preferable that the generated mist is sucked, and therefore a container that can withstand a negative pressure is preferable.
[0051]
The electrolytic cell 3 includes a barrel type, a flat plate type, and the like, and any of them can be used. However, a barrel electrolytic cell is preferable in terms of easy handling of recovered copper, and simple and inexpensive facilities. In this barrel electrolytic cell, a cylindrical barrel main body is supported so as to rotate in the horizontal direction, and a large number of copper pipes having a diameter of several tens mm and a length of several tens mm are accommodated in the barrel main body. . When electrolysis is performed using this barrel electrolytic cell 3, the copper dissolved in the copper etching waste liquid precipitates on the outer surface of the copper pipe, and the copper pipe grows and becomes thicker, and the outer diameter gradually increases. growing. In addition, since almost all copper is removed from the treated waste liquid after the completion of the electrolysis, it can be used for neutralizing the alkaline waste liquid.
[0052]
A part of the processing waste liquid after the completion of the electrolysis is used for mixing the copper etching waste liquid supplied into the electrolytic tank for the next electrolysis, and is used in the electrolytic tank and the intermediate tank to precipitate high-purity copper. Will remain. Since almost all copper is removed from the treated waste liquid by electrolysis, the remaining part can be used for neutralizing the alkaline waste liquid and can be effectively used.
[0053]
Further, a preferred embodiment of the present invention when a large amount of copper etching waste liquid is treated using a barrel electrolytic tank will be described with reference to FIG.
In this apparatus, a copper etching waste liquid is first supplied to a heating device 1 and heated to 60 to 80 ° C., and then introduced into a heat retaining tank 2 and kept at the same temperature range for 0.5 to 10 hours to decompose hydrogen peroxide. I do.
[0054]
The copper etching waste liquid from which the hydrogen peroxide has been decomposed is supplied to each of the three barrel electrolytic cells 11, 12, and 13 provided with the valve 17 opened, and the valve 17 is closed after the supply is completed. At that time, a part of the copper separation treatment waste liquid after the copper was deposited by the previous electrolysis is left in the barrel electrolysis tanks 11, 12, 13 and the intermediate tank 15, and the electrolysis tanks 11, 12, 13 In this case, the supplied copper etching waste liquid and the copper separation treatment waste liquid are mixed, and copper and COD components in the copper etching waste liquid are diluted.
[0055]
Thereafter, the valve 18 is opened, and the copper separation treatment waste liquid after the copper stored in the intermediate layer 15 is precipitated is cooled by the cooling device 16 and circulated and refluxed to each of the electrolytic cells 11, 12, and 13. Overflow therefrom to mix and stir the etching waste liquid in each electrolytic cell to make it uniform, and then perform electrolysis in each electrolytic cell. It is technically difficult to increase the size of the barrel electrolyzer because it is technically difficult to install three electrolyzers in parallel, and it is easy to install a plurality of small electrolyzers. Because you can.
[0056]
Further, the reason why the copper separation treatment waste liquid after the copper is deposited is circulated and refluxed in each of the electrolytic cells 11, 12, and 13 is to make the concentration of the etching waste liquid in each electrolytic cell uniform and to perform the electrolysis appropriately. is there. Further, the reason why the overflowed waste liquid is cooled and cooled by the cooling device 16 in the course of being circulated and refluxed in each electrolytic cell is to consider the temperature resistance of the barrel electrolytic cell. Is preferred.
[0057]
【Example】
Hereinafter, the present invention will be specifically described based on Examples, but it is needless to say that the present invention is not limited at all by the Examples, and is specified by the claims. Absent.
In this embodiment, the treatment of the copper etching waste liquid was performed using the apparatus having the basic configuration shown in FIG. The heating device 1 was a container (internal volume of 300 L) provided with a quartz tube heater, the heat retaining tank 2 was a container (internal volume of 4000 L) insulated with glass wool, and the electrolytic cells 11, 12, and 13 used barrel electrolytic cells. .
[0058]
The copper etching waste liquid used for the electrolysis contains 38 g / L of copper, 15 g / L of hydrogen peroxide, 105 g / L of sulfate, and contains propanol and cyclohexylamine as oxygen peroxide stabilizers, and the COD is 1920 mg / L. Met. 200 L of this waste liquid was supplied to the heating device 1 each time, heated to 80 ° C., heated, and then sent to the heat retaining tank 2 for storage. The heating was repeated 10 times, and all the waste liquid after the heating was sent to the heat retaining tank 2.
[0059]
The copper etching waste liquid having a total volume of 2000 L after the liquid was sent 10 times was stored for 7 hours, and hydrogen peroxide was decomposed during the storage. Thereafter, the valve 17 was opened, the valve 18 was closed, and the solution was sent to the barrel electrolytic cells 11, 12, and 13 for electrolysis. The electrolytic cell and the intermediate layer (capacity: 6000 L) store a total of 2,000 L of copper separation waste liquid after the copper was deposited in the previous electrolysis. , The copper etching waste liquid in each electrolytic cell was mixed with the copper separation treatment waste liquid.
[0060]
Next, the valve 17 is closed and the valve 18 is opened to circulate the copper separation waste liquid in the intermediate tank 15 to each of the electrolytic tanks 11, 12, and 13. The copper etching waste liquid in the same tank is the copper separation waste liquid. And then overflows from each electrolytic cell and returns to the intermediate layer 15. By repeatedly circulating and moving the copper etching waste liquid and the copper separation processing waste liquid in this manner, the concentrations of the respective components of the copper etching waste liquid in the electrolytic cells 11, 12, and 13 are made uniform. By this homogenization, the copper and COD components in the copper etching waste liquid are diluted, and the concentrations of the components after dilution are copper 18.8 g / L, hydrogen peroxide 70 mg / L, sulfate 106 g / L, and COD is 1469 mg. / L.
[0061]
Thereafter, a constant current electrolysis was performed by supplying 500 A DC for 50.6 hours in the electrolytic cell. The copper in the barrel electrolytic cell was reduced by this electrolysis, and was precipitated on the outer surface of the copper pipe serving as the cathode in the tank. The outer diameter of the copper pipe grew with an increase in the amount of electricity used, and the copper pipe grew. The composition of the waste liquid after the completion of the electrolysis was 100 mg / L of copper, 0 mg / L of hydrogen peroxide, 108 g / L of sulfate, and 1002 mg / L of COD. The weight of copper deposited on the outer surface of the copper pipe was 74.4 kg, and the purity was 99.7%, which was high purity.
[0062]
In this electrolysis, the obtained copper had a high purity of 99.7%, was firmly fixed to the copper pipe of the base material in appearance, and had a distinctive red color unique to copper. . In the case where the electrolysis was performed without mixing and diluting with the copper separation treatment waste liquid after the copper was precipitated as in the case of this example, the precipitated copper was desorbed some time after the deposition, and was placed in the electrolytic cell. The deposits were cumbersome to handle.
[0063]
【The invention's effect】
In the method for treating a copper etching waste liquid according to the present invention, hydrogen peroxide in the etching waste liquid is removed by heating before being introduced into the electrolytic cell, and copper dissolved in the etching waste liquid is removed in the electrolytic cell. Almost completely recovered by decomposition. Therefore, there is no generation of sludge that requires landfill disposal as in the conventional case of processing by requesting a waste disposal contractor, and it is possible to reduce a great deal of disposal cost associated therewith.
[0064]
Further, before the electrolysis, the hydrogen peroxide is previously removed by thermal decomposition as described above, and the recovery of copper and the decomposition of the hydrogen peroxide recently developed by the present inventors are performed in an electrolytic cell together. It is possible to avoid the decomposition of hydrogen peroxide generated prior to the deposition of copper at the cathode, which is a problem of the copper etching waste liquid treatment technology that can be used, and to avoid wasting power due to the decomposition.
[0065]
Furthermore, the present inventor has also developed a technology that can greatly improve the current efficiency for copper deposition that can avoid this power waste, but also in this technology, the copper and hydrogen peroxide remaining in the etching waste liquid are: Since it is a batch process, the fluctuations in their concentrations after each process are large, and the fluctuations in the current efficiency due to the fluctuations in the composition ratio of the two are also large, and the new equipment capacity must be excessively increased. It has been found that there is a problem, and in the present invention, since hydrogen peroxide is removed in advance, the present invention is an excellent solution that can also solve this problem.
[0066]
The inventor of the present invention has recently developed a method of treating a copper etching waste liquid which can solve the new problem that the apparatus capacity must be excessively increased, and applied for the application immediately before the filing of the present application. In the invention of this application, it is necessary to use an inorganic acid such as sulfuric acid, and the use thereof causes an increase in cost. It should be particularly emphasized that the present invention also solves this problem. That is, it is possible to achieve an excellent operation effect.
[0067]
It should be further emphasized that the copper separation waste liquid after copper deposition used in place of the inorganic acid such as sulfuric acid used in the invention filed immediately before the filing of the present application was discarded in other factories or other product production lines. In the method for treating a copper etching waste liquid, not a sulfuric acid, but a sulfuric acid-containing waste acid discharged after the treatment, the copper etching waste liquid is used in a closed cycle. It is not only a waste liquid treatment method, but also an excellent technology for utilizing waste acid, which is excellent.
[Brief description of the drawings]
FIG. 1 shows a basic configuration of an apparatus for treating a copper etching waste liquid according to the present invention.
FIG. 2 shows a basic configuration of a preferable apparatus for treating a large amount of copper etching waste liquid.

Claims (5)

Sulfuric acid, a copper etching waste liquid containing a hydrogen peroxide stabilizer composed of hydrogen peroxide and an organic compound is heated to 60 to 80 ° C., and maintained at the same temperature range for 0.5 to 10 hours to decompose hydrogen peroxide. A method for treating a copper etching waste liquid that recovers a copper component as metallic copper by electrolysis, wherein COD is reduced by mixing a copper separation processing waste liquid after recovering the copper component as metallic copper before electrolysis. A method for treating a copper etching waste liquid, comprising: The method for treating a copper etching waste liquid according to claim 1, wherein the mixing of the copper separation treatment waste liquid after recovering the copper component as metallic copper is performed before or after decomposing hydrogen peroxide. The method for treating a copper etching waste liquid according to claim 1 or 2, wherein the electrolysis is performed after reducing the COD to 1500 mg / L or less. The method for treating a copper etching waste liquid according to any one of claims 1 to 3, wherein a residual hydrogen peroxide concentration after decomposing the hydrogen peroxide is 2.0 g / L or less. The method for treating a copper etching waste liquid according to any one of claims 1 to 4, wherein a part of the copper separation treatment waste liquid after recovering the copper component as metallic copper is used for neutralization of alkaline wastewater.

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