JPH04308097A - Device for removing metallic ion - Google Patents

Abstract

PURPOSE:To remove the trace copper ion in a liq. having a high content of Fe<2+> ion, for example. CONSTITUTION:An insulating pipe 3 is allowed to pierce an electrolytic cell 1, and a conductive filter bed 5 also used as a cathode is laminated oh the pipe 3. A meshy cathode feeder 6 is provided around the filter bed 5, and a rod-shaped anode 4 is inserted into the pipe 3. Since the pipe 3 to be laminated with the filter bed 5 is pierced with many water passage holes 31, a liq. to be treated in the electrolytic cell 1 is introduced into the pipe 3 through the filter bed 5. As the surface area of the cathode can be increased, the current density of the cathode is reduced while supplied with a requisite current, and the metal ion is selectively and effectively electrodialyzed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for removing copper ions from, for example, a copper-based iron chloride waste solution.

0002

[Prior Art] Generally, copper ions are contained in the waste liquid generated from the etching of printed circuit boards and the pickling of copper-based steel sheets in steel mills. Therefore, in order to prevent pollution, the copper ions are removed before being discharged into the sewer. Needs to be removed. As methods for treating such waste liquid, electrolytic methods using diaphragmless electrolytic cells or diaphragm electrolytic cells, solvent extraction methods, and the like are known, but none of them can provide a sufficient removal rate.

[0003] When processing a large amount of copper-based iron chloride waste solution after etching printed circuit boards with ferric chloride solution, for ease of operation, iron scraps are thrown into the waste solution to separate iron and copper. Copper ions are removed as metal by substitution with ions, and then chlorine gas is passed into the waste liquid, thereby chlorinating ferrous chloride to remanufacture ferric chloride.

[0004] This situation can be expressed as a chemical formula as follows.

[0005]

[Chemical 1] That is, the waste liquid before treatment contains ferrous chloride reduced by etching, cupric chloride as a product, hydrochloric acid, and unreacted ferric chloride. When iron scrap is input, ferric chloride first reacts with iron to form ferrous chloride, then cupric chloride and iron react to produce copper powder, which is removed by solid-liquid separation. . The ferrous chloride is then chlorinated to form ferric chloride.

[0006]

[Problems to be Solved by the Invention] However, the ferric chloride solution remanufactured by such a method contains about 50 to 200 ppm of copper ions, including the redissolution of copper. This level of copper ion concentration poses no problem when etching copper, but when etching iron-based or nickel-based materials, such as shadow masks, copper in the etching solution may precipitate on the material to be etched. This poses a problem, and it is also undesirable from the standpoint of pollution prevention if it is discharged directly into the sewer system.

The present invention has been made against this background, and an object of the present invention is to provide a metal ion removal device capable of removing copper ions from, for example, copper-based iron chloride waste liquid at a high removal rate. be.

[0008]

[Means for Solving the Problems] First, to explain the point of view of the present invention, for example, as mentioned above, the waste liquid after etching a printed circuit board with a ferric chloride solution is used as an anode and a graphite felt as an anode and a cathode, respectively. When electrolyzed, reactions shown by chemical formula 2 occur at the anode and chemical formula 3 at the cathode.

[0009]

[Case 2]

0010

[Chemical 3] Considering the cathode reaction based on equilibrium theory, the current density that can cause copper electrodeposition is the lowest, followed by the current density that can cause hydrogen evolution, and then the current density that can cause iron deposition. It's getting bigger. Therefore, when current is passed between the electrodes, copper electrodeposition should occur first. However, in the above-mentioned waste liquid, the concentration of iron ions is, for example, about 1600 times higher than the concentration of copper ions, so in reality, a large amount of iron electrodeposition and generation of hydrogen gas occur as side reactions. Further, when the pH is low and the hydrogen ion concentration is high, iron deposition does not occur, and the main reaction is the generation of hydrogen gas. Note that if the current value is reduced in order to suppress the electrodeposition of iron, the reaction will be slow and it will take a very long time to remove the copper in the electrolytic cell, or the device will become too large.

Therefore, the inventor of the present invention created the following device based on the idea of increasing the surface area of the cathode as much as possible. That is, the metal ion removal device of the present invention includes a rod-shaped soluble anode body and a cathode body, which is arranged so as to surround the anode body through a gap and is made of a conductive filtration layer, in an electrolytic cell. A liquid to be treated containing metal ions to be removed is supplied to the electrolytic cell and flows from the outside to the inside of the cathode body, and the flow path is the cathode body itself. shall be.

0012

[Operation] The liquid to be treated, for example, the above-mentioned copper-based iron chloride waste liquid, is pumped into the electrolytic cell and passes through the filtration layer constituting the cathode body. Since this filtration layer is a liquid resistor, the liquid to be treated does not enter the filtration layer locally but is dispersed and enters the filtration layer, and after passing through this layer, it rises along, for example, the anode body. It is discharged from above.
Here, the cathode body is formed into a cylindrical shape by, for example, graphite felt, so its surface area is extremely large.
Therefore, the current density can be increased while obtaining the required removal rate, and with the addition of the above-mentioned dispersion effect, the liquid to be treated can come into contact with the electrode portion where the current density is low over a wide range. As a result, the electrodeposition of iron and the generation of hydrogen are suppressed, and the electrodeposition of copper becomes main and occurs over a wide range. Since the cathode itself is a filtration layer, the deposited and fallen copper powder is filtered here.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view showing the entire embodiment of the present invention, and FIG. 2 is a perspective view showing the main parts thereof. In this embodiment, a drain chamber 2 equipped with a drain port 21 is provided at the top of a cylindrical electrolytic cell 1 having a water intake port 11 for the liquid to be treated at the bottom. The upper end is the drain chamber 2
An insulating pipe 3 made of an insulating plastic such as PVC is installed, which is open inward and whose lower end penetrates the electrolytic cell 1 and protrudes to the outside. This pipe 3 has a large number of water passage holes 31 formed in the pipe wall above the lower end. Further, a flange 32 is formed near the upper end of the pipe 3, and is fixed to the bottom surface of the drainage chamber 2 via this flange 32.

[0014] An anode body 4 made of a round iron rod that penetrates the drain chamber 2 from the outside is inserted into the pipe 3 to near the lower end of the electrolytic cell 1 through a gap.

The outer circumferential surface of the pipe 3 is wrapped with felt or sheet made of conductive fiber such as carbon or graphite, except for the vicinity of the lower end where the water passage hole 31 is not formed. A filtration layer 5 is constructed which also serves as a filter. Furthermore, a mesh-shaped cathode power supply body 6 made of, for example, titanium is arranged on the outer peripheral surface of the filter layer 5 so as to tightly cover the entire surface. In order to attach the cathode power supply body 6, for example, as shown in FIG. They may be joined via 61 and 62.

Next, the operation of the above embodiment will be described. First, copper waste liquid, which is a liquid to be treated, is pumped into the electrolytic cell 1 through the water inlet 11 by a pump (not shown), and the anode body 4 is
A voltage is applied between the cathode power supply body 6 and the cathode power supply body 6 by a DC power supply E. As the raw material copper waste liquid, for example, a waste liquid obtained after etching copper with a ferric chloride solution is decoppered by cementation using iron scrap, and a copper waste liquid that still contains trace amounts of copper ions is used.

As can be seen from the above structure, in order for the liquid to be treated in the electrolytic cell 1 to reach the drainage chamber 2, it must pass through the water passage hole 31 of the pipe 3 through the filtration layer 5, which also serves as a cathode body. Therefore, the filtration layer 5 acts as a water resistor, and the liquid to be treated permeates through the filtration layer 5 in a uniformly dispersed state, rising inside the pipe 3 along the anode body. Therefore, the liquid to be treated flows through the entire range of the filter layer 5, which also serves as a cathode body.

[0018] As explained in detail in the "effect" section,
The cathode body is arranged so as to surround the anode body 4, and since the cathode body itself constitutes a filter layer such as felt, it is possible to reduce the current density while passing the required amount of current. Electrodeposition of copper is suppressed and copper becomes the main electrodeposition. The copper powder that has precipitated and fallen out is also filtered within the filtration layer 5, but the permeated material descends within the pipe 3,
It is discharged from its lower end. On the other hand, the liquid to be treated from which copper has been removed is discharged from the drain port via the drain chamber 2. In the above embodiment, one electrode body, which is a combination of an anode body and a cathode body, is arranged in the electrolytic cell, but in the present invention, a plurality of such electrode bodies are arranged in the electrolytic cell to increase the throughput. Alternatively, as shown in FIG. 3, for example, two electrolytic cells each having a plurality of electrode bodies may be connected in series to perform multistage treatment.

Next, the results of an experiment conducted using the two-stage apparatus shown in FIG. 3 will be described. First, as an apparatus, the water inlet of the second-stage electrolytic cell 1B is connected to the drain port of the first-stage electrolytic cell 1A via the gas-liquid separator 7, and the water inlet of the second-stage electrolytic cell 1B is An electrode body with 10 electrode bodies having a similar structure is used. and ferrous chloride, ferric chloride and ferric chloride
When the liquid to be treated containing copper was supplied to the electrolytic cell 1A at a flow rate of 100 l/hr and a current of 20 A per cell, the metal ion concentration in each part was as shown in Table 1.

[0020]

[Table 1] As can be seen from this experimental example, copper ions can be removed at a high removal rate with the above-mentioned apparatus. Note that in this example, Fe3+ reoxidized in electrolytic cell 1A is mainly removed, but by adjusting the flow rate and the winding diameter of the filtration layer that also serves as the cathode body, it is not necessary to use a two-stage type. Of course, functions can be obtained.

In the above-described embodiment, the insulating pipe 3 serves as a holder for the filtration layer 5, but it is not necessary when a strong filtration layer 5 is used. In addition, the mesh-like cathode feeder may be of any type as long as it can provide a large contact area with the felt or sheet-like cathode. You may use the thing which has. Furthermore, in order to force-feed the liquid to be treated into the electrolytic cell, a method may be adopted, for example, by providing a head difference between the storage tank for the liquid to be treated and the electrolytic cell, without using a pump.

[0022] Furthermore, if the point at which the filter layer is clogged with deposited metal and the point at which the anode body melts and becomes unusable are aligned, maintenance will be easy because the entire electrode body can be replaced. Also, there is no need to waste the anode body.

[0023]

According to the present invention, since the cathode body made of a conductive filter layer is arranged to surround the rod-shaped anode body, the surface area of the cathode body in the liquid to be treated is extremely large. As a result, the current density in the cathode body can be reduced while passing the required current, and therefore metal ions can be selectively deposited. Moreover, since the filtration layer acts as a resistor for the liquid to be treated, the liquid to be treated flows into the filtration layer over a wide range, and for this reason, a large amount of Fe2+ is present in, for example, copper-based etching iron waste liquid. Trace amounts of copper ions in the liquid can be removed with high efficiency.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a perspective view showing essential parts of the same embodiment.

FIG. 3 is an explanatory diagram showing another embodiment of the present invention.

[Explanation of symbols]

1 Electrolytic cell 2 Drainage chamber 3 Pipe 4 Anode body 5. Filtration layer that also serves as a cathode body 6 Cathode power supply

Claims (1)

[Claims] Claim 1: A rod-shaped soluble anode body and a cathode body, which is arranged so as to surround the anode body through a gap and is made of a conductive filtration layer, are placed in an electrolytic cell, Removal of metal ions characterized in that a liquid to be treated containing target metal ions is supplied to an electrolytic cell and flows from the outside to the inside of the cathode body, and the flow path is the cathode body itself. Device.