JPS605890A - Electrolytic refining method of metal - Google Patents

Abstract

PURPOSE:To improve considerably the anode current efficiency in the stage of electrolysis by using a non-conductor for the surface of an anode basket facing a cathode and inserting an insoluble electrode into the position of the anode basket spaced furthest from the cathode. CONSTITUTION:A cathode 2 and an anode basket 8 are disposed to face each other via a diaphragm 7 in electrolytic refining of a metal. The basket 8 is formed of a non-conductor and an insoluble electrode 9 is inserted into the position spaced furthest from the cathode 2. Coarse metallic lumps 5 are then packed in the basket. If electrolysis is performed in this state, the flow of current is through the electrode 9 the lumps 5 the cathode 2 and the greater part of the electric power supplied to the anode is used for the dissolution of the lumps 5. The cathodes 2 and the anodes may be placed alternately to face each other and parallel electrolysis is performed in the above-mentioned method. The continuous electrolytic refining is made possible and energy consumption is reduced by such method.

Description

DETAILED DESCRIPTION OF THE INVENTION 4r EilJ relates to an improvement in the electrolytic refining process of metals using an anode basket.

When refining crude metal electrolytically, the crude metal as shown in Figure 1 is usually cast into a plate shape to serve as an anode, a thin plate of refined metal or a mother plate of a different metal is used as the cathode, and electrolyte 3 is used as the cathode. Arrange them facing each other or alternately in the 'rl
i Ir? It is common to do so.

If the anode slime generated from the anode is likely to peel off from the anode, the anode is wrapped in a cotton cloth. By the way, when using such an electrolytic method, the anode/ is not necessarily dissolved uniformly, so in order to prevent the anode from falling off during electrolysis, the electrolysis is stopped when the thickness has decreased to a predetermined level, and the anode/ I am trying to remove the anode and replace it with a new anode. The pulled up anode scrap can be reused by being cast into a plate again, but this reused portion is always recycled within the process.

Particularly when the metal is expensive, the interest burden on such recycling cannot be ignored and becomes a factor that increases refining costs. In order to reduce the refining cost by completely eliminating this recycled content, as shown in Fig.
It is thought that it is sufficient to charge the metal into a corrosion-resistant metal basket (referred to as anode scrap) and use this basket as an anode. To prevent the anode slime generated from the anode from adhering to the cathode Ω, place d! between the cathode and the anode basket Ω.
A diaphragm 7 made of J cloth may be provided.

According to this method, the crude metal lump is melted within the anode, so that no anode scrap is generated. However, if the metal lump becomes small, it will fall from the net 1 of the basket and mix into the slime to some extent.

Furthermore, if the ant slime that settles at the bottom of the electrolytic cell under the gamma node bathtub B is taken out as appropriate, electrolysis can be carried out almost continuously. For example, if you want to replace the cathode once the cathode λ has been electrodeposited to a certain thickness, you only need to take a break to replace the cathode, and if you are refining a metal that will be electrodeposited in granular or powder form on the cathode, you can use a scraper. Since it is sufficient to provide a metal powder and constantly scrape it off, if the scraped metal powder can be continuously taken out, there is no need to replace the cathode λ, and continuous electrolytic refining can be performed.

However, when the above method was actually tried, it was found that the anode current efficiency was abnormally low.

For example, an experiment was conducted to electrolytically refine lfl silver using a titanium basket as an anode, stainless steel as a cathode, and an aqueous silver nitrate solution as an electrolyte.The anode current efficiency was about 1%.

The reason for this is that the current flow route is from Basket B to 1F.
This is thought to be because fl metal lump S → cathode. Basket B with respect to cantos is closer to cathode λ than coarse gold lump, and the current flows directly from basket I-B to force sortos. This is supported by the fact that bubbles were observed from the cathode replacement side of Basket B, but no bubbles were observed from the other sides. If the anode current efficiency is extremely lower than the cathode current efficiency, the metal ion concentration in the electrolyte will rapidly decrease, making it impossible to continue electrolysis unless a considerable amount of metal ions are replenished.

The present invention eliminates these drawbacks and provides an electrolytic refining method that can significantly improve anode current efficiency.

To achieve this objective, the present invention provides that at least the surface of the anode basket facing the cathode is made of a non-conductor,
An insoluble electrode is placed in the anode basket at a position farthest from the cathode for electrolysis.

FIG. 3 is a diagram conceptually showing the electrolysis method of the present invention. Third
In the figure, the cathode Ω and the anode basket g are arranged opposite to each other with a diaphragm 7 interposed therebetween, and the 7/l' Haskera l-g is composed of a nonconductor, and the cathode λ in the basket g is the largest one. An insoluble electrode w is inserted into the position and the coarse gold nodules k are filled. If electrolysis is carried out in such a state, the current flow will be from the electrode W to the coarse metal lump S to the cathode Ω, and most of the power supplied to the anode will be used for melting the coarse gold lump IW. In FIG. 3, the surface of the anode basket g facing the cathode may be made of a nonconductor, and the other surfaces may be made of a metal material that also serves as an electrode. The electrode wire may be plate-shaped, mesh-shaped, or grid-shaped. Insoluble electrode? . Titanium is the most affordable material. Since the anode basket is charged with 1 ffl metal lump, it needs to have appropriate strength, and is preferably made of a metal base lined with rubber or resin, but it may also be made of synthetic resin as long as it has sufficient strength. The example shown in FIG. 3 shows a case where the cathode λ and the anode basket g are arranged to face each other, but the cathode and the anode may also be arranged to face each other alternately for parallel electrolysis. In such a case, the anode box may be made of a nonconductor, and the insoluble electrode may be inserted in the middle of the box facing the cathode. In this way, the insoluble electrode will be at the farthest position from the opposing cathode.

The present invention has significantly improved the anode 'C(f) and fluidity, making continuous electrolytic refining possible over a long period of time and contributing to energy savings.

Exception cylinder diameter 2.02m, inner cylinder diameter /,! ;3m, depth/,
07m resin-lined annular electrolytic cell with diameter /, /
A stainless steel cylindrical cathode with a height of 7 m is installed, and 72 anode baskets each having a stainless steel base lined with PvC resin are arranged along the outer cylinder, and a titanium plate is placed on the outer cylinder side of each basket. A filter cloth diaphragm is provided between the anode basket and the cathode to divide it into an anode chamber and a cathode chamber, and Ag gθg
/7! Electrolysis was carried out using an electrolytic solution of IJO Otsu Jl. The bottom of the cathode chamber is flat, and a part of the bottom is provided for taking out the deposited silver scraped off with a scraper. The bottom of the anode chamber is a sloped gutter, and an anode slime outlet is provided at the lowest end. The electrolyte was supplied to the cathode chamber and extracted from the anode chamber for circulation. The electrolytic solution extracted from the anode chamber is filtered to remove floating anode slime, and is treated in a -f91f and liquid purification process to reduce the concentration of the liquid.
1+d conditioned and returned to the electrolytic cell. While putting coarse silver ingots into the anode basket and replenishing them one by one,
Electrolysis was carried out continuously for several months at a cathode current density of 1l-00A7/m, and approximately 5,000 pieces of purified silver powder (purity 99
．． 99%). The anode current efficiency was 7S%.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of a general electrolytic refining method in which crude metal is made into a plate shape and used as an anode for electrolysis. Figure 2 is an electrolytic refining method in which crude metal is made into a lump and placed in a metal basket and used as an anode for electrolysis. Figure 3 is an explanatory diagram of the electrolytic refining method according to the method of the present invention. Anode, co-cathode, 3. Electrolyte, G.
Filter cloth, S... Coarse metal ring, B - Metal basket, 7...
Diaphragm, g...nonconductor anode slime, w...electrode. Is 1illt ＼ ＼＾5、l”hi心゛、11
1 ii 8 ;1 Agent: Patent attorney Katsunari Donakamura □

Claims (1)

[Claims] (1) Pack the 211 metal lump into an anode basket,
In a metal electrolytic refining method in which an anode basket and a cathode plate are electrolyzed by lining them up in an electrolytic solution L″L or alternately facing each other, at least the surface of the anode basket facing the cathode is made of a nonconductor, and the anode A metal annotation refining method characterized by inserting an insoluble electrode in the basket at the farthest position from the cathode and performing electrolysis.