JP2533916Y2 - Electrode plate for electrolytic recovery from precious metal electropolishing wastewater - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention electrolytically recovers a noble metal from a noble metal electropolishing wastewater as a gold-silver alloy (87% gold, 13% silver) and converts the deposited noble metal into a foil. The present invention relates to an electrode plate for electrolytic recovery from waste precious metal electropolishing waste liquid which can be recovered with excellent workability by peeling.

[Prior art] Conventionally, for example, in a factory for performing electropolishing of precious metal products, gold contained in electropolishing waste liquid is precipitated together with a noble metal to which a reducing agent (such as zinc dust) is added, for example. This was again dissolved in aqua regia and then reduced and solidified using a reducing agent such as sodium sulfite to recover.

[Problems to be Solved by the Invention] However, in the above-mentioned recovery means, base metals other than noble metals are co-precipitated, and these base metals must be removed. There is a drawback that it takes time to handle.

It is also conceivable to try to obtain a foil by electrolytic recovery, but in the conventional electrode plate, the deposited gold is difficult to peel off, or when it is easy to peel off, when it is easily peeled, it is peeled off in a small scale like an electrolytic cell. It was dropped and the collection efficiency was very poor.

This invention is intended to solve the above-mentioned disadvantages of the conventional example, and the deposited gold-silver alloy can be easily peeled off from the electrode plate, and can be efficiently recovered in a clean foil form from the precious metal electropolishing waste liquid. It is intended to provide a collecting electrode plate.

[Means for Solving the Problems] That is, the electrode plate for electrolytic recovery from the noble metal electropolishing waste liquid of the present invention is formed by anodizing the surface of a mirror-finished stainless steel plate and then contacting with an acid to form an oxide film. It is characterized by having done.

[Effect] The electrode plate for electrolytic recovery from the noble metal electropolishing waste liquid according to the present invention was precipitated because the surface of the mirror-finished stainless steel plate was anodized and then contacted with acid to form an oxide film. Gold can be easily peeled off from the electrode plate, and can be efficiently recovered in a clean foil form.

[Example] Next, an example of an electrode plate for electrolytic recovery from a noble metal electropolishing waste liquid according to the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 1 denotes an electrolytic recovery device. The electrolytic recovery apparatus 1 is divided into a control unit 11 having a power supply, a circulating pump, a DC integrating ammeter, and the like, an electrolytic cell 12, and a plurality of chambers, and the number of chambers used can be increased or decreased according to the amount of liquid. And a storage tank 13 as described above.

The circulation pump includes a control unit 11, an electrolytic tank 12, and a storage tank 13.
The electrolytic solution is forcibly circulated through a piping system 14 disposed therebetween.

As shown in FIG. 2, the electrolytic cell 12 is supplied with an electrolytic solution from a supply port 21 provided at a lower part of the cell and a discharge port 22 provided at an upper part thereof.
From the tank 13. Electrode plates at predetermined intervals in the tank
23 are suspended vertically.

As the electrode plate 23, as shown in FIG. 3, a stainless steel plate 31 whose surface is mirror-finished is used.

Table 1 compares the purity and releasability of electrodeposited metal between stainless steel (electrode of the present invention) used as an electrode plate and an invar alloy (conventional electrode).

In addition, the electrode of this invention invention Example of Table 1 was produced as follows.

Anodize caustic soda 200g / as anodizing solution on the mirror-finished stainless steel (SUS304) plate surface, anodize with voltage 10V, treatment time 10 minutes, then acid with hydrochloric acid: water = 1: 4 and acid for 20-30 seconds Contact was made to form an oxide film.

Table 2 compares the state of the deposited metal and the peelability when stainless steel was used as the electrode plate (Example).

The electrodes of the present invention in Table 2 were prepared as follows.

The surface of the mirror-finished stainless steel plate was anodized using caustic soda 200g / as an anodizing solution at a voltage of 10 V for a treatment time of 10 minutes. Was formed.

Table 2 compares the state of the deposited metal and the peelability when stainless steel was used as the electrode plate (Example).

Table 3 shows the relationship between the surface roughness of the stainless steel plate and the releasability.

* "$ 500" in Table 3 indicates a fairly coarse mesh.

* “♯1500” indicates a fine class of mesh.

* "Blue stick" indicates an abrasive that can be mirror-polished.

By the way, during the above experiment, although the mirror-finished and anodized one peels off neatly, it has a drawback that the recovery efficiency is very poor because it is peeled off in small scales and dropped into the electrolytic cell during electrolytic recovery. It has been found. Therefore, in the present invention, the surface of the mirror-finished stainless steel plate 31 is anodized, and then brought into contact with an acid to form an oxide film 32 appropriately.
Is formed.

By the way, caustic soda 200g /
Preferably, the voltage is 10 V and the processing time is 10 minutes.

The acid is preferably, for example, hydrochloric acid: water = 1: 4, and the treatment time with the acid is suitably 20 to 30 seconds.

The thickness of the oxide film formed at this time is about 0.1 to 50 μm.

Electrode plate having oxide film 32 obtained by the above processing
In No. 23, the deposited gold could be easily peeled off from the electrode plate 23, and could be efficiently recovered in a clean foil form.

[Effects of the Invention] The electrode plate for electrolytic recovery from the noble metal electropolishing waste liquid according to the present invention formed a moderately oxidized film by anodizing the surface of the stainless steel plate mirror-finished as described above and then contacting it with acid. Therefore, the deposited gold can be easily peeled off from the electrode plate, and can be efficiently recovered in a clean foil form.

Further, since it does not take much time to process the electrode plate, gold can be electrolytically recovered at low cost as a whole.

[Brief description of the drawings]

1 is a perspective view of an electrolytic recovery apparatus, FIG. 2 is a perspective view of an electrolytic cell, and FIG. 3 is a cross-sectional view showing an embodiment of an electrode plate for electrolytic recovery from a noble metal electropolishing waste liquid of the present invention. DESCRIPTION OF SYMBOLS 1 ... Electrolysis recovery apparatus, 11 ... Control part 12 ... Electrolysis tank, 13 ... Storage tank 14 ... Piping system, 21 ... Supply port 22 ... Exhaust port, 23 ... Electrode plate 31 ... Stainless steel plate, 32 ... Oxide film

Claims (1)

(57) [Scope of request for utility model registration] 1. An electrode plate for electrolytic recovery from electropolishing waste liquid, characterized in that a mirror-finished stainless steel plate is anodized on its surface and then contacted with an acid to form an oxide film.