KR100311951B1 - Apparatus and method for treating a cyanide waste water using a electrolysis - Google Patents

Abstract

PURPOSE: A method for treating cyanide wastewater using electrolysis is provided, which is characterized in that to increase treatment efficiency, a chemical treatment using hydrogen peroxide is combined. CONSTITUTION: An apparatus for treating cyanide wastewater using electrolysis comprises a mixing reactor(10) for completely mixing plating wastewater with H2O2, an electrolysis part(20), an effluent part(30) for supplying electrolyzed plating wastewater to a reduction tank. The mixing reactor(10) has an inlet(11) for receiving both plating wastewater and hydrogen peroxide, and in addition an agitator(12) is installed in the mixing reactor for complete mixing. In the mixing reactor, supplied hydrogen peroxide resolve cyanide complex, and CN ion is converted to CNO ion(CN+ H2O2→ CNO+ H2O). Hydrogen peroxide is resolved into water in electric field, so under alkali condition, hydrogen peroxide shows oxidization effect only to cyanide complex, not affecting anode.

Description

Apparatus and method for treating a cyanide waste water using a electrolysis}

The present invention relates to an apparatus for treating cyanide plating wastewater using electrolysis, and more particularly, to an apparatus for treating cyanide plating wastewater using electrolysis in which chemical treatment using hydrogen peroxide is used simultaneously with a steel ball to increase current efficiency. It is about. The present invention also relates to a method for treating cyanide plating wastewater using electrolysis.

1 shows the treatment of plating wastewater according to the prior art.

As shown in Fig. 1, in order to treat the plating wastewater containing CN, Cr, acid, alkali and the like, the plating wastewater is first supplied to the flow regulating tank 1. Then, sodium hypochlorite (NaOCl) and caustic soda (NaOH) are added to oxidize cyan and oxidized in the first oxidizing tank 2 and the second oxidizing tank 3, respectively. When cyan is oxidized in this way, it is supplied to the reduction tank 4, and it reduces and then supplies it to the coagulation tank 5 and the precipitation tank 6, neutralizing by adding caustic soda (NaOH). When the plating wastewater is supplied to the settling tank 6 through this process, the sludge is discharged through an outlet located at the bottom of the settling tank 6, and the purified plating water is discharged to the outside.

The above-described treatment is a physicochemical treatment. In this process, sodium hypochlorite (NaOCl) is used as an oxidant to oxidize cyanide in an oxidizing tank. In addition, it is not possible to completely decompose cyanide in one step. Sodium (NaOCl) has a disadvantage of causing odor in the workplace due to the peculiar smell.

In addition, the intermediate product cyanide (CNCl) is produced during the oxidation process, such cyanide chloride (CNCl) is a component that is dozens of times more toxic than the toxicity of cyanide can directly affect the life of the worker.

In addition, such a physicochemical treatment method takes two to three times more cost than using electrolysis, and has a disadvantage in that the land use area and maintenance cost are excessively consumed because several types of tanks are used. In addition, cyanide compounds in the plating wastewater are cross-linked with various heavy metals. When using this physicochemical treatment method, excessive oxidizing agents and neutralizing agents are required to satisfy the emission allowance standard. There is a disadvantage that it does not meet the emission limit by lowering the sedimentation efficiency.

In addition, in order to treat the cyan-based plating wastewater, an electrolysis apparatus as shown in FIG. 2 was used.

That is, as shown in Figure 2, a plate-shaped electrode plate was used. As a method for increasing the current efficiency, sodium chloride (NaCl) and caustic soda (NaOH) were used in combination. At this time, the use of sodium chloride (NaCl) is because the chlorine ion of sodium chloride (NaCl) can be explained by two reactions in which cyanide is decomposed by electrons to decompose cyan, or electrons oxidize cyan.

In the following, the reason for using sodium chloride (NaCl) as an additive as described above will be described using a reaction scheme.

CuCN + NaCN → NaCu (CN) ₂

NaCu (CN) ₂ + NaCN → NaCu (CN) ₃

NaCu (CN) ₃ → 2Na ⁺ + Cu (CN) ₃ ^2-

Scheme 1 above is a reaction scheme of a copper cyanide plating solution, and the main component of the copper-added cyanide plating solution becomes a Cu (CN) ₃ ²⁻ type complex ion.

As described above, when electrolytically decomposing Cu (CN) ₃ ^2- form complex ions, which are the main components of the cyanide solution, in the negative electrode (cationic reaction) and the positive electrode (cyanide decomposition reaction), reaction schemes 2 and 3 React each.

Cu (CN) ₃ ^2- → Cu ⁺ + 3CN ^_

Cu ⁺ + e- → Cu (copper metal)

H ₂ + 2OH ^_ -2e- → 2H ₂ O

CN ^_ + 2OH ^_ -2e- → CNO ^_ + H ₂ O

2CNO ^_ + 4OH ^_ -6e- → 2CO ₂ + N ₂ + H ₂ O

Cu (CN) ₃ ^2- + 6OH ^_ -7e- → Cu ²⁺ + 3CNO ^_ + 3H ₂ O

4OH ^_ -4e- → O ₂ + 2H ₂ O

The copper cyanide plating solution reacts as in Schemes 1, 2, and 3, but when sodium chloride (NaCl) is used as an additive to improve the current efficiency, it reacts as in Scheme 4.

NaCl → Na ⁺ + Cl ^_

2Cl ^_ → Cl ₂ (g) + 2e-

Cl ₂ + 2OH ^_ + CN ^_ → CNO ^_ + Cl ^_ + H ₂ O

3Cl ₂ + 6OH ^_ + 2CNO ^_ → 2 (HCO ₃ ) ^_ + N ₂ + Cl ^_ + H ₂ O

Sodium chloride (NaCl) is added to achieve the same effect as in Scheme 4 above, but Cl ₂ affects anodization to form Fe (OH) ₃ hydroxide precipitate (sludge) in the alkaline state as in Scheme 5 Interferes with the transmission of the.

Fe + Cl ₂ → Fe ²⁺ + Cl ^_

Fe ²⁺ + 3OH ^_ → Fe (OH) ₃

As can be seen from the above schemes, when using an electrolysis device for the purpose of oxidizing cyanide compounds, increasing the electrical conductivity by using sodium chloride (NaCl) will not only produce excessive sludge, but also any anode other than platinum. Even if used, the anode does not last long and causes a problem of corrosion. And, due to the smell of chlorine itself has a disadvantage of deteriorating the environment in the workplace.

In addition, the use of the stainless electrode plate in the electrolysis device has the advantage that the life of the anode can last longer, there is a disadvantage that heavy metals such as chromium contained in the stainless is eluted. In addition, these electrolysis devices are low current, high voltage, high power cost and very high initial capital investment. At present, most of the domestic plating companies are small and small, so they can not be initially invested, and also meet the Cyan emission limit. I can't make it happen

Accordingly, the present invention has been made to solve the problems of the prior art as described above, to provide an apparatus for treating cyan-based plating wastewater using electrolysis that can improve the current efficiency by using a plurality of steel balls as an electrode. Its purpose is to.

In addition, the second object of the present invention is to change the polarity periodically to prevent corrosion, thereby prolonging the life of the electrode, as well as the electrolysis that can recover the copper and other heavy metals detached from the electrode as a raw material for reuse It is to provide a treatment apparatus for the cyan-based plating waste water used.

In addition, a third object of the present invention is to provide a method for treating cyanide plating wastewater using electrolysis, which protects an operator from odors and poisons by using hydrogen peroxide as an additive.

1 is a schematic view for explaining a treatment method of plating wastewater according to the prior art,

2 is a perspective view showing an electrolysis device according to the prior art,

3 is a schematic view for explaining the components of the cyan-based plating wastewater treatment apparatus using electrolysis according to an embodiment of the present invention,

4 is a schematic view for explaining an important part of the cyan-based plating wastewater treatment apparatus shown in FIG.

FIG. 5 is a block diagram for explaining an operation process using the apparatus for treating cyan-based plating wastewater shown in FIG.

Figure 6 is a photograph showing the degree of corrosion of the anode surface according to the type of anode material and additives, respectively.

♠ Explanation of symbols on the main parts of the drawing ♠

10: complete mixing reaction unit 11: inlet

12: stirrer 20: electrolysis unit

21: electrolysis tank 22: electrode separation tube

23, 24: electrode carrier 25: electrode conversion means

26 control means 27 rectifier

28: power 29: steel ball

30: outlet 40, 50: separator

According to the present invention for achieving the above object, in the cyan-based plating wastewater treatment apparatus using an electrolysis including an electrolysis unit to remove and remove heavy metals and harmful substances contained in the cyan-based plating wastewater. The electrolysis unit comprises: an electrolysis tank, an electrode separator tube positioned in the center of the electrolysis tank to separate the positive electrode and the negative electrode from each other, an electric carrier of the positive electrode positioned in the center of the electrode separator tube and connected to the positive electrode, and the electrode separation. An electroconductor of a cathode positioned between the tube and the electrolysis tank and connected to the cathode, and a plurality of steel balls respectively filled in the electrode separator tube and between the electrode separation tube and the electrolysis tank to form a positive electrode and a negative electrode, respectively.

In addition, according to the present invention, it further comprises an electrode conversion means for periodically converting the positive electrode and the negative electrode supplied to the electric carriers of the positive electrode and the negative electrode, the positive electrode and the negative electrode of the negative electrode is a stainless rod or steel resistant to corrosion Each is formed of a rod.

In addition, according to the present invention, in the method for treating cyanide plating wastewater using electrolysis to electrolyze and remove heavy metals and harmful substances contained in the cyanide plating wastewater, hydrogen peroxide (H ₂ O ₂ ) is added as an oxidizing agent. by decomposing the cyan compound formed of a complex salt, and oxidizing the CN ^{_ _} CNO ions into ion facilitates the electrolysis of cyan.

Hereinafter, with reference to the accompanying drawings, a preferred embodiment of the apparatus for treating cyanide plating wastewater using electrolysis according to the present invention and a method for treating the same will be described in detail.

3 is a schematic view for explaining the components of the apparatus for treating cyanide plating wastewater using electrolysis according to an embodiment of the present invention, and FIG. 4 is an apparatus for treating cyanide plating wastewater shown in FIG. 3. Figure 5 is a schematic diagram for explaining the important part of, Figure 5 is a block diagram for explaining the operation process using the cyan-based plating wastewater treatment apparatus shown in FIG.

As shown in Figure 3 and 4, the treatment apparatus of the plating wastewater of the present invention is a device for removing some of the heavy metal and cyan, a complete mixing reaction of mixing the incoming plating wastewater and hydrogen peroxide (H ₂ O ₂ ), etc. The electrolysis unit 20 for electrolyzing the unit 10, the plating waste water and the like mixed and supplied in the complete mixing reaction unit 10, and reducing the electroplating waste water, etc. electrolyzed in the electrolysis unit 20 It consists of the outlet 30 which supplies to a tank.

Here, the complete mixing reaction unit 10 is provided with the plating wastewater, and hydrogen peroxide (H ₂ O ₂₎ is the inlet (11) flowing at the same time, the plating wastewater and hydrogen peroxide flows through these inlets (11) (H ₂ O ₂₎ The stirrer 12 which mixes completely is provided. The complete mixing reaction unit 10 configured as described above may uniformly supply plating waste water and the like into the electrolysis unit 20. In addition, the complete mixing reaction unit 10 uses hydrogen peroxide (H ₂ O ₂ ) to break up a part of the cyan compound formed by the complex salt and hydrogen peroxide (H ₂ O ₂ ) to change some CN ^_ ions to CNO ^_ ions. A plug-flow reactor may be used as the reactor for addition. The use of hydrogen peroxide (H ₂ O ₂ ) is because it reacts as in Scheme 6.

CN ^_ + H ₂ O ₂ → CNO ^_ + H ₂ O, decomposition of some complex ions

As can be seen from the above Scheme 6, hydrogen peroxide (H ₂ O ₂ ) is only oxidative to the cyan compound in alkali and appears to have little effect on the anode because hydrogen peroxide (H ₂ O ₂ ) is decomposed into water in the electric field Judging.

In addition, the first separation plate 40 having a plurality of holes is formed at the upper portion of the complete mixing reaction part 10 so that the plating waste water, etc., completely mixed by the stirrer 12 may be supplied to the electrolysis part 20. It is installed. At this time, the first separator 40 is formed of an insulator so as to separate the positive electrode and the negative electrode from each other.

In addition, the upper portion of the first separation plate 40 is provided with an electrolysis unit 20 for electrolyzing the supplied plating waste water. The electrolysis unit 20 includes a cylindrical electrolysis tank 21 for storing plating waste water and the like. In the center of the electrolytic bath 21, the positive electrode and the negative electrode are separated from each other, but the electrode separation tube 22 is formed with a plurality of holes so that ions generated in the plating waste water and the like can move freely. At this time, the electrode separation tube 22 is formed of an insulator so as to separate the positive electrode and the negative electrode from each other.

In the center of the electrode separator tube 22 installed as described above, a positive electrode 23 (current corrector) of the positive electrode is installed, and between the electrode separator 22 and the electrolytic bath 21, a negative electrode 24 (current; corrector) is installed. At this time, the positive electrode and the negative electrode electric conductors 23 and 24 are each formed of stainless steel rods or steel rods resistant to corrosion.

In addition, four cathodes 24 are provided in the longitudinal direction of the electrolysis tank 21, and one is installed at the top and the bottom in the circumferential direction of the electrolysis tank 21, respectively. . The electroconductor 24 of the cathode is formed in this manner in order to maintain a low current density and prevent the voltage from rising.

The electrode carriers 23 and 24 of the positive and negative electrodes thus arranged are connected to the electrode converting means 25 and the control means 26 so as to periodically convert the positive and negative electrodes, and the electrode converting means 25 is a power source. It is connected to the rectifier 27 connected to (28).

As described above, a plurality of electrodes having a predetermined diameter inside the electrode separator tube 22 and between the electrode separator tube 22 and the electrolysis tank 21 in which the positive and negative electrode carriers 23 and 24 are installed, respectively. The steel balls 29 are each filled. By using a plurality of steel balls 29 in this way it is possible to maximize the surface area of the electrode.

The electrolysis unit 20 configured as described above reacts with a small amount of hydrogen peroxide (H ₂ O ₂ ) added first so that cyan ions can react more quickly.

In addition, a second separation plate 50 having a plurality of holes is disposed in the upper portion of the electrolysis unit 20 so that the electrolytic plating waste water and the like may be supplied to the treatment tank of the next stage through the outlet 30. At this time, the second separator 50 is formed of an insulator so as to separate the positive electrode and the negative electrode from each other.

In the present invention configured as described above, the injection of hydrogen peroxide (H ₂ O ₂ ) is not only suppresses the formation of a small amount of precipitate, it is added as a way to achieve the complete oxidation of cyan when injected by increasing the concentration of the cyan inlet. .

In the following, a treatment method using the cyan-based plating wastewater treatment apparatus configured as described above will be described in detail.

3 to 5, the cyan-based plating wastewater and hydrogen peroxide (H ₂ O ₂ ) are supplied through the inlet 11 of the complete mixing reaction unit 10. Then, the plating wastewater and hydrogen peroxide are evenly mixed by the operation of the stirrer 12 and supplied to the electrolysis unit 20 through the first separator 40. When the plating waste water or the like is supplied to the electrolytic part 20 in this way, a heavy metal of a cation such as copper is recovered at the cathode connected to the electrolytic carrier 23 of the cathode, and cyan at the anode connected to the electrolytic carrier 24 of the anode. This is broken down.

When the electrode is changed by the electrode conversion means 25 while the cation is recovered and the cyan is decomposed through this process, the cation is recovered and cyan is decomposed therein according to the changed electrode. In this way, the anode and the cathode are periodically switched to prevent the corrosion of the anode. Carbon particles, copper and metal grains generated by changing the polarity are particles that can act as an electron transporter rather than a mediator that prevents the flow of electrons.

When the cation is recovered and the cyan is decomposed in the electrolysis unit 20, the second separation plate 50 and the outlet port 30 are supplied to the neutralization settling unit and are processed in the same process as in the prior art.

In addition, in order to more effectively treat the cyanide compound contained in the plating wastewater, the cyanide plating wastewater treatment apparatus of the present invention configured as described above may be installed in two stages.

6 and Table 1 show the degree of corrosion of the anode surface according to the type of anode material and additives.

Anode Material ＼ Analytical Element Cr (ppm) Fe (ppm) Fe - 5.03 Fe-NaCl addition - 630.26 Fe-H ₂ O ₂ addition - 2.72 stainless 9.88 43.93 Stainless-NaCl added 41.13 371.39

As can be seen in Figure 6 and Table 1, when treating the plating waste water by adding hydrogen peroxide as in the present invention, it can be seen that the corrosion degree of the anode is significantly reduced. In other words, when used by adding hydrogen peroxide as in the present invention, it is possible to extend the life of the positive electrode.

As described in detail above, the method for treating cyanide plating wastewater using electrolysis according to the present invention uses hydrogen peroxide as an oxidizing agent to reduce the corrosion of the anode and extend the life of the anode, as well as to suppress the smell in the workplace. It can be improved.

In addition, the apparatus for treating cyan-based plating wastewater using the electrolysis of the present invention can increase the surface area using a plurality of steel balls, thereby lowering the current density applied to the electrode and improving the overall current efficiency.

In addition, the apparatus for treating cyan-based plating wastewater using the electrolysis of the present invention may recover and reuse copper and other heavy metals desorbed from the electrode as raw materials.

In addition, in the case of using the apparatus for treating cyanide plating wastewater using the electrolysis of the present invention, a conventional oxidation tank is unnecessary, so that the use site can be reduced, and the acidic liquid can be neutralized with the alkaline liquid contained in the plating wastewater. Therefore, the amount of caustic soda can be reduced.

Although the technical idea of the apparatus for treating cyanide plating wastewater using the electrolysis of the present invention and the treatment method thereof has been described together with the accompanying drawings, this is intended to exemplarily describe the best embodiment of the present invention. It is not.

In addition, it is obvious that any person skilled in the art can make various modifications and imitations without departing from the scope of the technical idea of the present invention.

Claims (4)

In the apparatus for treating cyanide plating wastewater using electrolysis comprising an electrolysis unit to electrolytically remove heavy metals and harmful substances contained in the cyanide plating wastewater, The electrolysis unit 20 is an electrolysis tank 21, an electrode separation tube 22 which is located in the center of the electrolysis tank 21 to separate the positive electrode and the negative electrode from each other, and the electrode separation tube 22 An electric current carrier 23 of the positive electrode positioned at the center of the electrode and connected to the positive electrode, an electric carrier 24 of the negative electrode positioned between the electrode separation tube 22 and the electrolysis tank 21 and connected to the negative electrode; And a plurality of steel balls 29 respectively filled in the electrode separator tube 22 and between the electrode separator tube 22 and the electrolysis tank 21 to form an anode and a cathode, respectively. Treatment device for cyanide plating wastewater using decomposition. 2. The cyan using electrolysis according to claim 1, further comprising an electrode conversion means (25) for periodically converting the anode and the cathode supplied to the electrical carriers (23, 24) of the anode and the cathode. Treatment equipment for system plating wastewater. 3. The treatment of cyan-based plating wastewater using electrolysis according to claim 1 or 2, wherein the electrolytic bodies 23 and 24 of the positive electrode and the negative electrode are formed of stainless steel rods or steel rods resistant to corrosion, respectively. Device. In the method for treating cyanide plating wastewater using electrolysis to electrolyze and remove heavy metals and harmful substances contained in the cyanide plating wastewater, Hydrogen peroxide (H ₂ O ₂ ) is added as an oxidizing agent to decompose the cyan compound formed by complex salt and cyanide plating waste water using electrolysis, which facilitates electrolysis of cyan by oxidizing CN ^_ ion to CNO ^_ ion. Treatment method.