JPS6312153B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention is an electrolytic deposition tank (hereinafter referred to as an electrodeposition tank) that electrically removes metal ions such as copper, lead, nickel, and chromium that are contained in high concentrations in industrial waste liquids, particularly in industrial waste liquids. related to). [Prior Art] Conventionally, electrodeposition tanks capable of recovering highly pure metal powder and metal foil have often been used as removal and recovery devices for the metal ions contained in waste liquid discharged from the Metsuki factory and the like. In order to economically process a large amount of waste liquid in a short time using this method, it is necessary to arrange a large number of electrodes closely together and to minimize the gap between the electrodes. It was necessary to make significant improvements to the structure of the electrodeposition tank and the method of arranging the electrode plates, taking into account the stirring method of the electrodeposition solution. In addition, human and mechanical safety is ensured against flammable and explosive gases such as oxygen and hydrogen gases generated during electrodeposition, and corrosive chlorine gas and foul-smelling gases generated when chlorine ion organic substances are contained in the waste liquid. We must also consider the issue of securing security. Conventional stirring methods include a method of stirring the lower part of the electrode group using a stirring blade, and a method of stirring using liquid circulation using a pump and aeration. The most economical stirring method is said to be the aeration stirring method using air, but it has the disadvantage that air bubbles rise between the narrow electrodes, which increases the voltage between the electrodes and increases electricity costs. In addition, to treat dangerous and unpleasant generated gases, the electrolytic deposition tank is used as a nearly sealed type, and the gas is sucked in using a fan, etc., but more equipment than necessary must be installed to ensure the explosion-proof and corrosion-resistant properties of the equipment used for treatment. It didn't happen. [Object of the Invention] An object of the present invention is to provide an electrodeposition tank that can improve power efficiency and safety by improving the stirring of the solution in the electrodeposition tank and the arrangement of electrode groups. [Structure of the Invention] The present invention is characterized in that the tanks are separated by communicating with each other at the bottom by a partition wall equipped with an overflow weir at the upper end, and one tank is used as a pumping tank equipped with an air list diffuser pipe for circulating the electrolyte solution. none,
The other tank is an electrode group tank in which multiple electrode plates for electrodeposition are arranged vertically and perpendicularly to an overflow weir, and the pumped electrodepositing solution flows down between the electrode plates, and the deposited metal accumulates at the bottom of the tank. The present invention relates to an electrodeposition tank for metal ion-containing waste liquid, characterized in that it is provided with a section. The present invention will be explained below based on the drawings. FIG. 1 is a side sectional view of the electrodeposition tank, and FIG. 2 is a plan view. An electrodeposition tank 1 having a sloping bottom is separated by a partition wall 2 which communicates the bottom and has an overflow weir at the upper end. One separated tank is used as a water pumping tank 4 equipped with a diffuser pipe 3 for air lift. Air lift gas is generally air, and in special cases inert gas is used. As shown in FIG.
A plurality of these are arranged to form an electrode group arrangement tank 6. That is, the electrodeposited solution pumped in the water pumping tank 4 overflows the overflow weir and reaches the electrode tank 6.
After flowing down toward the bottom of the electrode tank in parallel and evenly between the electrode groups, it rises again from the communication part at the lower end of the partition wall 2 to the pumping tank 4, and as the circulation is repeated, metal ions are deposited on the cathode 5b by electrodeposition. It is deposited as a metal and processed. At this time, the air and inert gas used for pumping water is released from the water surface of the pumping tank, so it does not mix between the electrode groups, and the gas generated by electrodeposition also increases the amount of water pumped. Rather than rising, the gas migrates to the pumping tank along with the flow and scatters from the pumping tank, so the gas existing between the electrodes is small and the interelectrode voltage resistance is minimized, leading to a reduction in power costs. By increasing the amount of gas for air lift, the number of times of circulation within the tank increases, which is effective in increasing the electrodeposition effect and power efficiency as well as dissipating, diluting, and pumping the generated gas to the gas processing equipment. However, there is a theoretical limit to increasing the number of circulations, so in order to further increase the electrodeposition effect, the electrode shape may be changed to a wire mesh shape, punched metal shape, etc. in order to give stronger agitation to the electrolyte flowing between the electrode plates. It is preferable to use a perforated plate in the form of expander metal. On the other hand, this has the effect that the shape of the metal deposited on the cathode plate 5b is not foil-like but granular or dendritic, and is easily peeled off from the electrode plate and sedimented by the circulating electrodeposition solution. A precipitated metal accumulating section 7 having an inclined side surface is provided at the bottom of the electrodeposition tank, making it easy to concentrate and draw out the deposited metal. Furthermore, as for the electrodeposition tank structure, as shown in Fig. 3, two of the electrodeposition tanks shown in Fig. 1 are combined and the lower part of the central partition wall is connected to serve as an accumulation part for the deposited metal, or as shown in Fig. 4, an air lift is used. A structure in which the pumping part is provided in the center of the tank is practical. Figure 5 shows a rectangular electrodeposition tank used for comparison with the present invention, and the electrode group arranged inside is exactly the same as in Figure 1, with an aeration pipe provided from the bottom of the electrode group in the direction in which the electrode group is arranged. . The present invention will be explained below based on Examples and Comparative Examples. [Example, Comparative Example] Using the electrolytic cells shown in Figures 1 and 5, the amount of aeration air is the same, and the electrodeposition conditions such as current density, current concentration, and amount of current are completely the same, and the sulfuric acid shown in Table 1 is used. Figure 6 and Table 3 show the results of electrodeposition treatment of plating waste liquid containing copper under the electrodeposition conditions shown in Table 2.

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〔Effect of the invention〕

As described above, in the present invention, by using a part of the electrodeposition tank as a pumping tank and a part as an electrode group arrangement tank, it is possible to avoid the direct aeration method from the bottom of the electrode group for stirring, and Since the electrode group is arranged perpendicularly and vertically to the overflow weir, the electrodeposited solution continuously pumped up by air lift flows down and circulates between the electrode plates evenly many times, so that the electrode plates and metal ions are Since sufficient contact can be made between the two, extremely high power efficiency can be obtained.
Dilution, dissipation, and pressure delivery of the various gases generated can also be accomplished using air or inert gas used in air lifts. In addition, by making the electrode a porous electrode,
The stirring effect of the electrolyte solution flowing down and circulating between the electrodes was further strengthened, resulting in a significant increase in power efficiency.

[Brief explanation of the drawing]

1 and 2 are a cross-sectional view and a plan view of an electrodeposition bath according to the present invention, FIGS. 3 and 4 are cross-sectional views of applied examples, and FIG. 5 is a cross-sectional view of a comparative example of the present invention. FIG. 6 is a graph showing the processing results of an example of the present invention and a comparative example. Explanation of symbols, 1... Electrodeposition tank, 2... Partition wall, 3... Air lift diffuser, 4... Water pumping tank, 5a... Anode plate group for electrodeposition, 5b... Excellent cathode for electrodeposition, 6... Electrode group arrangement Tank, 7... Electrodeposited metal accumulating section, 8... Electrodeposited metal, 9... Circulating electrodeposition solution water flow, 10... Air bubbles.

Claims (1)

[Scope of Claims] 1. A partition wall equipped with an overflow weir at the upper end allows the tanks to be separated by communicating with each other at the bottom, and one tank is used as a water pumping tank equipped with an air lift diffuser pipe for circulating the electrolyte solution. The other tank is an electrode group arrangement tank in which multiple electrode plates for electrodeposition are arranged vertically and perpendicularly to the overflow weir, and the pumped electrodeposition solution flows down between the electrode plates, and the deposited metal is deposited at the bottom of the tank. An electrodeposition tank for metal ion-containing waste liquid, characterized in that it is provided with a collection section. 2. An electrodeposition tank for metal ion-containing waste liquid, characterized in that the electrode plate for electrodeposition is a porous plate.