JPS58130292A - Recovering device of dissolved metal in solution - Google Patents

Abstract

PURPOSE:To recover metals quickly and efficiently on a cathode by subjecting a soln. dissolved therein with metals to electrolytic reaction to electrodeposit dissolved metals on electric conductive granular materials, then dissolving the same in an aq. cyanide soln. under the presence of air and electrolyzing the same. CONSTITUTION:This recovering device consists of an electrolytic reacting device A and an electrolytic recovering device B. A waste plating soln. 2 dissolved, for example, gold and silver is introduced through a conduit 3 into a storage tank 1. While the soln. 2 is circulated, an electric power source 15 is turned on to effect electrolytic reaction in a cathode chamber 10, so that gold and silver are electrodeposited on electrically conductive granular materials 13. After the residual waste soln. in an electrolytic cell 7 is discharged, an aq. cyanide soln. 19 is circulated in an electrolytic chamber 16 to dissolve the gold and silver deposited on the materials 13 in the soln. 19. When the concn. of the gold and silver increases in the chamber 16, the switch 22 of an electric power source 21 is turned on to effect electrolytic reaction so that the gold and silver are deposited on a cathode 18 whereby the gold and silver are recovered as a dense metallic plate.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recovery device for metals, particularly dissolved metals in a solution, for recovering all of gold and silver from a solution in which they are dissolved. This invention relates to a dissolution and recovery device in a solution that includes a decomposition and recovery device (plague) and recovers gold and silver extremely quickly and efficiently.

BACKGROUND OF THE INVENTION Solutions containing various types of gold and silver, such as wastewater from matting factories in which metals, particularly gold and silver, have been dissolved, are subjected to recovery treatment using various devices in order to reuse the gold and silver.

However, the above-mentioned known collection devices all have the drawbacks of requiring a dog-like device, being time-consuming and expensive, and having poor collection efficiency.

The inventor uses a special collector to electrodeposit dissolved metal in a solution onto electrically conductive particulate matter, dissolves the metal on this particulate material in an aqueous cyanide solution, and quickly and efficiently recovers the metal by electrolysis. The present invention was completed by developing a device for this purpose.

An object of the present invention is to provide a recovery device for dissolved metals in a solution that can recover metals extremely quickly and efficiently.

In order to achieve the above object, the present invention (1) includes an electrolytic reaction device and an electrolytic recovery device, the electrolytic reaction device includes an electrolytic cell, the electrolytic cell is disposed within the electrolytic cell, and the electrolytic cell is arranged in the electrolytic cell. an electrolytic diaphragm that separates the battery into an anode chamber and a cathode chamber, a main anode and a main cathode disposed in the anode chamber and cathode chamber, respectively, and electrically conductive granular material and electrically insulating granular material filled in at least the cathode chamber. The electrically conductive particulate matter in the mixture is arranged so as to exhibit the same polarity as the respective main electrodes without causing a bipolar phenomenon in the anode or cathode chambers, and The electrolytic recovery device electrodeposits the dissolved metal in the solution onto the electrically conductive particulate material by causing an electrode reaction to occur in a solution containing the dissolved metal. an electrolytic chamber having an anode and a cathode and electrolyzing the cyanide aqueous solution in which the metal is dissolved to collect the metal in the aqueous solution on the cathode; 〇Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.〇 Fig. 1 shows a specific example of the apparatus according to the present invention, of which part A is an electrolytic reaction apparatus. (collector) and B are the electrolytic recovery device (break) 0 These A and B devices will be explained in sequence OA The electrolytic reaction device 7 is an electrolytic cell. 8 is arranged, and the electrolytic cell 7 is separated into an anode chamber 9 and a cathode chamber 10 by this diaphragm 8.The electrolytic diaphragm 8 includes a normal electrolytic diaphragm, an ion exchange membrane, a particulate material group 13 described below,
A synthetic resin plate with a large number of pores that do not allow 14 to pass through,
A ceramic plate, an unglazed plate, a synthetic fiber cloth, etc. may be used, but it is best to use a wooden plate such as an ice cube plate in order to advance the metal precipitation reaction.

Further, the electrolytic diaphragm 8 may be used in a plurality of plates, for example, two plates in contact with each other.

Further, on one side of the anode chamber 9 and cathode chamber 10 described above, a main anode 1 and a main cathode 12 (these are made of graphite, for example, and can also be collectively referred to as "main electrodes") are provided. - Also, both the anode chamber 9 and the cathode chamber 10 or at least the cathode chamber IO contain 1:3 electrically conductive particulate material and 1:3 electrically insulating particulate material.
Regarding the arrangement of the mixed granular material group described above, the main electrode plate 1 of the 13 groups of electrically conductive granular material is
1 and 12, so that the electric resistance value increases as the distance between the opposite electrodes increases, and the mutual contact between the electrically conductive particulate materials 13 is not completely cut off. In this way, the electrically conductive particulate material 13 and the electrically insulating particulate material 14 are mixed and arranged, and this arrangement expands the electrode reaction surface, and moreover, the surface of each electrically conductive particulate material 13 causes a bipolar phenomenon. Main electrode plate 11゜12
In order to achieve such an advantage, the size, proportion, material, etc. of the electrically conductive particulate material 13 and the electrically insulating particulate material 14 should be changed.
The electrically conductive particulate material 13 in the present invention may be set to the optimum condition depending on the characteristics of the electrolytic solution and other conditions.
For example, normal granular graphite, granular metals that are not attacked by the electrolyte to be treated, or granular alloys, etc. Further, the above-mentioned electrically insulating particulate material 14 includes, for example, glass beads, silica gel, synthetic resin particles, ion exchange resin particles,
Ceramic grains, etc.

In order to perform an electrode reaction using the electrolytic reaction apparatus A of the present invention as described above, a solution to be treated is applied between the main electrodes 11 and 12 by an external power source 15 while applying a potential difference in a batch or continuous manner. What is necessary is just to guide it into the space where the particulate material is arranged and allow it to pass through.

By passing in this manner, an oxidation reaction is effectively carried out in the isolation chamber 9, and a reduction reaction is effectively carried out in the cathode chamber 10.

When a solution in which metals such as gold and silver are dissolved is passed through the cathode chamber 10 and subjected to an electrode reaction, the gold and silver in the solution are electrodeposited onto the electrically conductive particulate material.

There are many reaction systems affected by this, for example,
In the anodic reaction, X +408-6e-+XO3+2H++H2OXO
3+)-I20-2 e-+X 04 + 2 H+(
In the formula, X represents a halogen element. ) 2804 2e-+8208 Mn04- e -Mn04'2C+"+ 8H20-6e 42CI04"+16H
+pP -2e -+ pd+ 20Mn -2e-+Mn OXygen Carrier as V, Mn,
Oxidation of organic compounds using Cc, C+, etc., Kolbe reaction, decomposition of organic substances...rogenated cyanide compounds, and others.

In the cathodic reaction, U”+ 2e −+U” Ca”+e−+Cu ME!”+ne→M (where M is Zn, Fe, Ni, Sn, Pb, Cu, H
g, Ag.

Indicates any one of Pt, Au, Cd, etc. ) Carbonyl compounds real alcohols, nido 011 compounds → amino compounds, hydrogenation of organic unsaturated compounds, nido 1
) hydrogenation of imino compounds, hydrogenation of imino compounds, and others. Therefore, by using the electrolyzer A of the present invention, it can be applied to the removal or detoxification of harmful substances in industrial wastewater, and to secondary and secondary batteries. When the area of the electrode is increased by bringing it into contact with the main electrode plate, the electrically conductive particulate matter on the side closer to the counter electrode becomes extremely highly polarized than the electrically conductive particulate material inside, and as a result, the reaction occurs at the counter electrode. This results in intense, high current densities on nearby electrically conductive particulate matter, which does not significantly increase the electrode area. Therefore, in the device A of the present invention, by appropriately blending an electrically insulating particulate material group into the electrically conductive particulate material group to be brought into contact, lengths and shorts are created in the chain of the electrically conductive particulate material group from the main electrode, and the direction of the opposite electrode is created. We took into consideration that the electrical resistance value increases as the distance increases, and devised so that the electrochemical reaction proceeds almost evenly on the entire electrically conductive particulate material group.
It is possible to significantly expand the electrode surface area, that is, the reaction field. What must be noted here is that when a large number of electrically insulating particulate materials are combined and arranged to the point where they completely cut off contact with each other, the electrically conductive particulate materials become bipone as described above. Four phenomena are induced, and redox reactions proceed at both ends of the same granular soil.

In addition, in the device A of the present invention, the diaphragm used to advance the electrolytic reaction can be formed with various grooves as described above, and in fact, good results can be obtained by using synthetic fiber cloth, unglazed board, porous plastic board, asbestos board, etc. . However, when metal ions in an aqueous solution are electrolyzed and metal is deposited on the sub-electrode using synthetic fiber cloth, pore plastic, etc., when the amount of precipitated metal increases, the metal continues to grow and extends toward the anode, and eventually Penetrating through the diaphragm, the positive and negative electrodes are electrically single-circuited, resulting in extremely poor electrolytic efficiency. In addition, when a bisque plate is used, the apparatus A of the present invention
Because of the presence of fillers such as, it is easily damaged and may become single. However, by using a wooden board for the diaphragm, these defects are eliminated and the device exhibits excellent functionality, which is maintained for a long time.

That is, in the apparatus A of the present invention, by using a wooden board as a diaphragm, it is possible to perform a metal precipitation reaction for the first time, and it can be made to withstand industrialization without being damaged by the slightest shock. Of course, in addition to this wooden board, it is natural to use the aforementioned synthetic fiber cloth, unglazed board, porous plastic board, asbestos board, etc.The wooden board is swollen by the electrolyte and its surface is weak against oysters. If so, this can also be laminated with synthetic fiber cloth.

As described above, in the device AK of the present invention, the electrically conductive particulate material 13 and the electrically insulating particulate material 14 are arranged as shown in FIG. Since it is involved as a reaction field, the reaction field is expanded and a sufficient potential can be obtained.Therefore, it has strong oxidizing or reducing power and exhibits excellent properties not found in conventional products. Furthermore, in the apparatus A of the present invention, an electrolytic diaphragm 8 is arranged between the main anode and the main cathode, and this diaphragm separates the electrolytic cell 7 into an anode chamber 9 and a cathode chamber 10. Even if the counter electrode is not installed separately from the group of substances, if it is not used for reaction separately in each chamber, the counter electrode must be installed quite far from the group of particulate materials, which makes the device large. However, in the device A of the present invention, the diaphragm is of a type in which all the anodes and cathodes are shared, so there is no need to install the counter electrode apart from the particulate matter group, and therefore the device is miniaturized and simplified. Below, the device A of the present invention will be described in more detail using experimental examples.

[Experimental example-1] This experimental example fd, 8 acid 2009/l, copper ion (Cu) 5
In the process of depositing metallic copper from a f/l electrolytic solution by cathodic reaction, there are two methods: the method using the electrolytic device A of the present invention and the other three methods, namely, the already patented activated carbon-filled bipolar cell (hereinafter 'A'). (hereinafter referred to as sXB method), a graphite-filled bipolar cell (hereinafter referred to as sXB method I), and a mixed-filled bipolar cell (hereinafter referred to as ``C method'') under the same electrolytic conditions. Make it.

When using the electrolytic reaction device A of the present invention, length x width x
A vinyl chloride electrolytic cell with a height of 70 x 70 x 100 mm was partitioned into two chambers: an X chamber of 70 x 50 m+ and a Y chamber of 70 x 2fJ x 100 m+ using a knotless test plate diaphragm with a thickness of 5 mm. 65X100 at both ends of both chambers
Place one X5+m graphite plate each, and fill both X%Y chambers with a mixed granular material group containing crushed graphite with a diameter of 2 to 3 and glass beads with a diameter of 3wn in a volume ratio of 6:4. did.

The electrolytic solution +00- is injected into the device A of the present invention, and
In the A, B, and C methods, the length x width x height is 70 x 70.
65 as positive and negative polar plates in the PVC electrolytic cell of Kari00kun.
X 1 (IOX 5 fMl graphite plate each)
Between the electrodes, 3 pieces of spherical activated carbon, 2 to 3 pieces of spherical activated carbon, 2 to
A mixture of 3fi crushed graphite grains, 2 to 3 pieces of crushed graphite, and 3mm vinyl chloride pellets in a volume ratio of 1:3 was filled between the poles of A, B, and C.
A bipolar tank filled with the method was prepared, an external power source was connected so as to have both positive and negative poles, the electrolytic solution 100- was injected, and electricity was applied for a period of time at IA. The reason why the particulate matter was blended at a ratio of 1:3 in Method C is that in this case, depolarization was observed from around 1:3. Hereinafter, the results of each method are shown in Table 1.

Table 1 Method for treating amount of copper deposited by each method Amount of copper deposited (■) Method of device A of the present invention 468 Method A 165 Method B 22 Method C 265 As a result, in the electrolytic method using device A of the present invention, the conventional filling Bipolar tank (UK Patent No. 1279650, British Patent No. 1362704, German Patent Publication No. 2148402)
It has been confirmed that this method is superior to the reaction field expansion method using the method described above.Moreover, the apparatus can be made smaller.

[Experimental Example 2] This experimental example uses the external power connection path of the device A of the present invention in [Experimental Example 1], and uses 200 tons of glucose, 7 tons of glucose,
Calcium carbonate 150 f/l, bromine 25y7't.

100ml of electrolyte solution. was injected, the temperature was kept at 23-25°C, and electrolysis was continued for addition at 3A, yielding 6.77 calcium gluconate.

In this way, when the apparatus A of the present invention is used, the oxidation reaction of organic substances can also proceed effectively.

[Experimental Example-3] In this experimental example, an experiment was conducted on the relationship between the composition ratio of particulate materials used in the apparatus A of the present invention and the electrolytic reaction effect.

The equipment used in this experiment was the same as that used in [Experiment Example-1], and the material and shape of the particulate matter group were also the same.
We decided to change only this blending ratio and examine the reaction effect of Cu +2e→Cu. The electrolytic solution and amount used were also the same as in [Experimental Example-1]. The experimental results are shown in Figure 2.

As a result, in order to deposit metallic copper from this electrolyte, it is necessary to
If you use graphite grains of three sizes and glass beads of 3 mm, the composition ratio is graphite: glass beads.
It has been confirmed that a capacity ratio of 1:1.5 to 1.5:1 is particularly effective, and the device can also be miniaturized.

[Experimental Example-4] In this experimental example, toxic potassium cyanide was treated using the apparatus of the present invention.
In terms of the effect of oxidative decomposition and detoxification, two to three pieces of crushed magtite particles are used as the conductive particulate material, and two to three pieces of vinyl chloride pellets are used as the insulating particulate material, and the capacity ratio of the particulate material group is determined. l:1. The equipment used was the same as in [Experimental Example-1], except that the power supply connections were reversed. The electrolyte used was KCNloo ppm 100-. The results are shown in FIG. As a result of this experiment, it was confirmed that the apparatus of the present invention can effectively and more quickly decompose potassium cyanide at low concentrations, which cannot be achieved by ordinary electrolytic methods.

[Experimental Example-5] This experimental apparatus has the same format as [Experimental Example-1], with an anode chamber of 30t1 and a cathode chamber of 701, a diaphragm made of saran cloth and a knotless cypress sheet metal with a thickness of 5 sugars. Ag! M/l, KCN
A 50 t/l electrolyte was circulated through the cathode chamber and the anode chamber, and a current of 100 A was applied from an external power source to advance the silver precipitation reaction. The electrolyte used was 500 t and 3
Continuous operation was performed for 00 hours.

Table 2 shows the results of silver plate printing in this case.

Table 2 Differences in diaphragm and amount of gold plate coming out Diaphragm Amount of silver plate coming out Anode and cathode single-layered cypress plate 24.87 kg None Saran cloth 3.2 kg Warming time approx. This shows that the selection of the diaphragm is important in the case of metal precipitation reactions.

B. Electrolysis recovery device This device includes an electrolysis chamber 16 and a dissolution chamber, and FIG. 1 shows an example in which the dissolution chamber is used in combination with the cathode chamber 10 of the electrolysis reaction device A. Of course, the dissolution chamber can be provided separately from the cathode chamber 10.

In the dissolution chamber (cathode chamber 10), the metal electrodeposited on the particulate material 13 is dissolved in the cyanide aqueous solution in the presence of air.

This cyanide aqueous solution is introduced into the electrolytic chamber 16 through the conduit 6. Further, the electrolytic chamber 16 has an anode 17 and a cathode 1 on both side walls.
8, electrolyzes the cyanide aqueous solution 19 in which metal is dissolved in the dissolution chamber, and collects the metal in the aqueous solution in the form of a plate on the cathode 18.

In addition to the electrolytic reaction device A and the electrolytic recovery device B described above, the apparatus of the present invention can be provided with a storage tank 1 for storing a solution in which metal is dissolved, for example, a plating waste solution, if necessary. This reservoir 1 is connected to the cathode chamber 10 by a conduit 4.4a such that the solution circulates from the reservoir 1 through the cathode chamber 10 to the reservoir 1.

Further, the electrolytic chamber 16 is configured such that the aqueous cyanide i19 circulates from the electrolytic chamber 16 to the electrolytic chamber 16 via the cathode chamber 10.
0 on the conduit side. In addition, pHP2, l in Figure 1
5 is a pump, 5a, 5b, 5c, and 5d are pulps, 21 is a power source, and 22 is a switch.

The apparatus according to the present invention constructed in this manner first closes the pulps 5b and 5d, and then closes the pulps 5a.

5c is opened, and in this state, the plating waste liquid 2 containing dissolved gold and silver, for example, is introduced into the storage tank 1 through the conduit 3. Next, the pump Pl is operated to circulate the plating waste liquid 2 from the storage tank l to the storage tank 1 via the conduit 4, the cathode chamber 10 and the conduit 4a, while the power supply 15 is turned on, and the plating waste liquid 2 is caused to undergo an electrode reaction in the cathode chamber 10. Gold and silver in the plating waste solution 2 are electrodeposited onto the electrically conductive particulate matter 13.

Next, the operation of the pump R is stopped, the pulps 5a and 5c are closed, and the residual waste liquid in the electrolytic cell 7 is discharged from a drain concavity (not shown), and then the pulps 5b and 5d are opened and the pulps 5a and 5c are closed.
2 to circulate the cyanide aqueous solution 19 in the electrolytic chamber 16 from the electrolytic chamber 16 to the electrolytic chamber 16 via the conduit side, the cathode chamber 10, and the conduit 6. The aqueous cyanide solution 19 is introduced into the cathode chamber 10 via line J) by spraying the aqueous cyanide solution onto the granular material 13, 14 in the form of a shower or spray. At this time, if the top of the cathode chamber 10 is opened to the air, the particulate matter 1 with gold and silver attached in the cathode chamber 10
In step 3, a cyanide aqueous solution is sprayed in the presence of air. That is, the substance 13 comes into contact with air while wet with the cyanide aqueous solution, so that the air acts as an oxidizing agent, and the gold and silver attached to the particulate material 13 are quickly dissolved in the cyanide aqueous solution. dissolved in Therefore, in apparatus B of the present invention, gold and silver can be dissolved quickly and efficiently by using only the cyanide aqueous solution as a dissolving solution for gold and silver. Such cyanide aqueous solutions include cyanide soda aqueous solutions, etc.
Various types can be used.

The aqueous cyanide solution containing gold and silver is then led from the bottom of the cathode chamber 10 through the conduit 6 to the electrolytic chamber 16.

The electrolytic chamber 16 has an anode 17 and a cathode 18 disposed on both side walls, and when the cyanide water @ Shigeru has a high concentration of dissolved gold and silver in the electrolytic chamber 16, the power source 21 is turned on.
When the switch 22 is turned on, electrolysis occurs, and gold and silver in the aqueous solution are recovered as a tightly twisted metal plate on the cathode 18 by electrolysis. Note that oxygen gas is mainly generated from the anode 17. Graphite is mainly selected as the material for the anode 17, and stainless steel is selected as the material for the cathode 18.

Furthermore, the cyanide aqueous solution 919 in the electrolytic chamber 16 is electrolytically treated as described above to recover gold and silver, and then passed through the conduit side.
By operating a pump P2 disposed at an arbitrary location on the conduit side, it is guided to the cathode chamber 10 and can be reused.

In this way, in the apparatus B of the present invention, since the aqueous cyanide solution can be reused, no waste liquid is generated, which is economical and does not cause pollution problems.

The present invention will be explained in detail below using experimental examples.

Experimental example l Experiments were conducted using the apparatus of the present invention shown in FIG.

First, close the pulps 5b and 5d, and then close the pulps 5a and 5c.
In this state, pour gold plating F3 into liquid 2 through conduit 3.
was introduced into storage tank 1. Next, the pump P+ is operated to circulate the gold plating waste liquid 2 from the storage tank 7 through the conduit 4, the cathode chamber 10, and the conduit 4a to the storage tank L, and then the power supply 15 is turned on.
The gold plating waste liquid 2 was subjected to an electrode reaction in the cathode chamber 10, and the gold in the gold plating waste liquid 2 was electrodeposited onto the electrically conductive particulate material 13.

Next, the operation of the pump P1 is stopped, the pulps 5a and 5c are closed, and the remaining waste liquid in the electrolytic cell 7 is discharged from the drain cock, and then the pulps 5b and 5d are opened and the pump P2 is activated to drain the cathode chamber 10. IIDψNaCN in particulate matter 13.14
The water solution was sprayed from the conduit 20 at a rate of 10 mt/min in the form of a shower. A 1 am2 stainless steel plate and a graphite plate were placed in the electrolytic chamber 16, and these were used as the cathode 18 and anode 17, respectively, and the switch 22 of the power source 21 was turned on to conduct electrolysis by flowing a current of 0.3 A. After 3 hours, gold was deposited on the stainless steel cathode 18.

Experimental Example 2 An experiment was conducted under the same conditions as Experimental Example 1 except that silver plating waste liquid was used instead of gold plating waste liquid. After three hours, all the silver on the particulate matter 13 had been dissolved, and silver was deposited on the stainless steel plate cathode 18 in the electrolytic chamber 16.

Experimental example 3 In this experiment, the dissolution rate of silver was investigated.

Using the same apparatus as in Experimental Example 1 and under the same conditions as in Experimental Example 1, the granular material with gold attached was treated, and as a result, the dissolution rate was 21 microns/hour at 200C. The dissolution method used in silver refining, in which scissors are immersed in curing powder and air is blown into it, was almost at this speed.

In this way, the present invention can overcome the conventional method of electrolyzing only with cyanide,
That is, unlike the air suction method, the dissolution rate for silver is approximately five times faster, making it a very useful invention.

[Brief explanation of the drawing]

Figure 1 shows a cross-sectional view of a specific example of the device of the present invention, Figure 2 shows a graph showing the relationship between the tdF2 material composition ratio and the amount of copper electrodeposition, and Figure 3 shows the electrolysis time and potassium cyanide decomposition rate. A graph showing the relationship between 1... Storage tank, 2... Plating waste liquid, 3.4.4a16, Rib,... Conduit, 5a, 5b,
5c. Respiratory conductive particulate material, 14... Electrically insulating particulate material, 1
5.21... Power source, 16... Electrolytic chamber, 17... Anode, 18... Cathode, 19... Cyanide aqueous solution, 22...
- Switch, A...electrolysis reaction device, B...electrolysis recovery device. Patent Applicant: Nanasei Kogyo Co., Ltd.

Claims (1)

[Scope of Claims] (1) The electrolytic reaction device includes an electrolytic reaction device and an electrolytic recovery device, and the electrolytic reaction device includes an electrolytic cell, and is disposed within the electrolytic cell, and the electrolytic cell is connected to an anode chamber and a cathode chamber. A mixture of an electrolytic diaphragm to be separated, a main anode and a main cathode arranged in the anode chamber and the cathode chamber, respectively, and an electrically conductive particulate material and an electrically insulating particulate material filled in at least the cathode room. The electrically conductive particulate matter in the mixture is arranged so as to exhibit the same polarity as the respective main electrodes without causing a bipolar phenomenon in the anode chamber or cathode chamber, and the molten metal The solution is subjected to an electrode reaction to electrodeposit the dissolved metal in the solution onto the electrically conductive particulate material, and the electrolytic recovery device collects the metal electrodeposited onto the particulate material in the presence of air. A dissolution chamber for dissolving the metal in the aqueous cyanide solution, and an electrolytic chamber having an anode and a cathode for electrolyzing the aqueous cyanide solution in which the metal is dissolved and collecting the metal in the aqueous layer on the cathode. A device for recovering dissolved metals in solution. (2. In the apparatus according to claim 1, the melting chamber is a cathode chamber in an electrolysis reaction device, the cathode chamber is connected to the electrolytic chamber through a conduit, and the metal (3) Percentage In the apparatus according to claim 1, there is further provided a device for storing a solution in which a metal is dissolved. An apparatus comprising a storage tank, the storage tank being connected to the cathode chamber by a conduit so that the solution circulates from the storage tank through the cathode chamber to the storage tank. (4) Claim 1 or In the apparatus according to claim 2, the electrolytic chamber is connected to the cathode chamber by a conduit so that the cyanide aqueous solution is circulated from the electrolytic chamber to the electrolytic chamber via the cathode chamber. 2. The device according to item 1, wherein the metal is gold or silver.