JPH01162789A - Method and device for recovering metal deposited on carrier - Google Patents

Abstract

PURPOSE:To recover the metals deposited on carriers with extremely little equipment by eluting the metals by an electrolyte contg. hydrochloric acid in an anode chamber, permeating the metals through neutral films into a cathode chamber, then reducing and depositing the metals. CONSTITUTION:The anode chambers 3 are formed on both sides of an electrolytic cell 1 and the anode chamber 4 is delineated at the center by two sheets of the liquid permeable neutral films 2. Anodes 5 and cathodes 6 are provided to the respective chambers. The alumina carriers 7 on which Pd and Pt are deposited are housed in a fixed bed state in the anode chambers 3. The electrolyte contg. the hydrochloric acid of the prescribed concn. is then supplied to the anode chambers 3 and is permeated through the neutral films 2 into the cathode chamber 4. The electrolyte is filtered by a filter 9 via a circulation line 8 and is thereby electrolyzed. The deposited metals are, therefore, eluted as ions and the ions permeate the neutral films 2 and enter the cathode chamber 4 where the metals are reduced and deposited to the metal simple substance. The carriers 7 in the anode chambers 3 are discharged from a cylindrical body 10 for air lifting by the compressed air from air valves 11 and the fresh carriers 7 are successively supplied from the upper part of the anode chambers 3.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is directed to eluting metals and/or metal compounds as metal ions from a carrier supporting a metal and/or a metal compound, particularly a catalyst carrier for automobiles, and converting the metal ions into metal ions. It relates to a method for recovering a single substance and a method for use in carrying out the method.

(Prior art and its problems) Various metals, especially platinum group metals, are widely used as catalytically active substances for various chemical reactions or automobile catalysts, or as parts such as contacts of electronic devices.

The performance of these catalysts and parts deteriorates over time, and eventually they reach the end of their service life and are discarded, but precious metals such as platinum group metals are particularly expensive, so they cannot be recovered and reused. It is economical and also leads to effective use of resources.

Based on this viewpoint, various methods have been attempted to recover various metals, particularly noble metals supported on carriers, but each method has its own technical drawbacks. First, the mainstream method for eluting noble metals on a carrier is the aqua regia dissolution method, in which powdery or granular noble metal-containing carriers are dissolved in aqua regia, which is a mixed acid of 1 part nitric acid and 3 parts hydrochloric acid. It has many drawbacks such as: In other words, (a) high temperatures are required to dissolve aqua regia, (b) NOX gas is generated during dissolution,
(C) In order to increase the elution efficiency, it is necessary to improve the precious metal concentration, and (d) There are disadvantages such as powder or granules being taken out with the eluate, and therefore a large amount of energy is required for heating. This causes unavoidable inconveniences such as consuming the NOX gas, requiring equipment and labor to detoxify the NOX gas, reducing dissolution efficiency, and complicating cleaning operations for removing powder or granules.

Moreover, in order to recover the precious metal separated from the carrier by the aqua regia dissolution method, the following methods have been adopted, but each method has its own drawbacks.

i) Chemical reduction method In this method, a reducing agent such as formic acid, oxalic acid, hydrazine, sodium borohydride, etc. is added to a solution containing precious metal ions to be recovered to reduce the precious metal ions to metals. However, the above-mentioned reducing agents are all expensive and increase the recovery cost, and in order to add the reducing agent, the solution after metal recovery is subjected to various treatments (for example, pH adjustment, COD removal, etc.). The disadvantage is that it must be played back.

ii) Metal substitution reduction method In this method, a metal whose oxidation-reduction potential is more base than that of the noble metal (e.g. zinc, aluminum) is added in the form of powder or granules to a solution in which a noble metal, etc. is dissolved. This method reduces the noble metal ions that are present in the ionizing process to a noble metal state, but since other metals are added, it has the same drawbacks as the chemical reduction method.

iii) Electrolytic recovery method In this method, dissolved metal ions are electrolytically deposited onto a cathode and then recovered by peeling off from the cathode, or electrically conductive particles are added to a solution and the metal ions are deposited on the cathode. This is a method of electrodepositing metal. However, in this method, prior to electrolysis, it is necessary to isolate the easily soluble chlorocomplex in aqua regia by evaporation to dryness and dissolve it in hydrochloric acid to form a hydrochloric acid acidic chlorocomplex, so it is necessary to evaporate a large amount of liquid. Moreover, in cathodic electrodeposition, the metal to be reduced is deposited on the cathode, so in order to recover the metal, it is necessary to stop the electrolytic operation and peel off the metal deposited on the cathode, which greatly reduces operational efficiency. In addition, the method using electrically conductive particles requires modifying the electrolytic cell to have a complicated structure suitable for the use of the electrically conductive particles, which increases the cost of modification. There are drawbacks.

iv) Chemical recovery method In this method, a solution in which metal ions are dissolved is concentrated and denitrated to form a metal chloride, and then the chloride is dissolved in warm water or dilute hydrochloric acid to chemically recover it from the chloride solution. In Although,
The drawback is that it requires a large number of steps and increases costs.

The aqua regia method described above has various drawbacks that lead to high costs, and requires the use of completely different processes for eluting metals from the carrier and recovering the metals, so it is not satisfactory in terms of cost and operation. It wasn't possible.

In other words, in metal recovery operations from waste catalysts, etc., one of the most important issues is how to obtain metals cheaply and easily, and electrolysis has been proposed as an innovative method to replace the aqua regia method.

This electrolysis method is a method in which chlorine is generated by electrolysis in an electrolytic tank equipped with an insoluble electrode using hydrochloric acid as an electrolyte, and the chlorine-containing electrolyte is brought into contact with a carrier supporting a precious metal to elute the precious metal. In this method, the electrolytic solution containing the eluted precious metal is reduced in the cathode chamber of the electrolytic cell and deposited on the cathode.

The electrolytic method avoids the use of expensive chemicals and does not produce by-products of harmful substances that cause pollution, so it is attracting attention as an excellent method for recovering precious metals. However, it is natural that further improvements are desirable even in this electrolytic method, which has a significant technical advantage over the aqua regia method.

For example, in the precious metal recovery method disclosed in JP-A-62-158833, hydrochloric acid is electrolyzed in an electrolytic cell to obtain chlorinated hydrochloric acid, which is taken out of the electrolytic cell and placed in an appropriate container to support precious metals. The noble metal is eluted by contacting with a carrier prepared by
In this method, a solution containing the eluted noble metal is circulated to the cathode chamber of the electrolytic cell, reduced therein, and the reduced noble metal is deposited on the cathode and recovered.

In this method, the precious metals on the carrier are eluted outside the electrolytic tank, so equipment for eluting the precious metals is required and the installation of a circulation line is essential.Moreover, since the precious metals are deposited on the cathode, the electrolytic It is necessary to periodically stop the process and recover the precious metal from the cathode.Therefore, there is a particular need for an economical precious metal recovery method that is simpler in terms of equipment and operation.

(Object of the Invention) In view of the drawbacks of the prior art described above, the present invention provides a method for recovering metals supported on a carrier using an electrolytic reaction device having a simpler structure, and a method used in the method. The purpose is to provide a device for

(Means for Solving the Problems) The present invention provides, firstly, that a metal and/or a metal compound is supported in the anode chamber of an electrolytic cell that is divided into an anode chamber and a cathode chamber by a liquid-permeable neutral membrane. accommodating a carrier, supplying an electrolytic solution containing hydrochloric acid to the anode chamber to electrolytically generate chlorine and eluting the metal and/or metal compound as a corresponding metal ion into the electrolytic solution; A method for recovering a metal supported on a carrier, which comprises transmitting a metal through the neutral membrane into the cathode chamber, reducing it to an elemental metal in the cathode chamber, and depositing the metal. an anode chamber in which a carrier carrying a metal compound is accommodated, and the metal and/or metal compound is eluted into the electrolyte as a corresponding metal ion by chlorine generated by electrolyzing an electrolyte containing hydrochloric acid; and a cathode chamber for reducing and precipitating metal ions in the electrolyte into corresponding metal elements;
a liquid-permeable neutral membrane that partitions the electrolytic cell into the anode chamber and the cathode chamber; and means for permeating the electrolyte in the anode chamber through the neutral membrane and into the cathode chamber. This is a device for recovering metals supported on a carrier.

The present invention will be explained in detail below.

In the present invention, the formation of metal ions by elution of metals on a carrier by chlorinated hydrochloric acid generated by electrolysis of hydrochloric acid is carried out in the anode chamber of an electrolytic cell by accommodating the carrier in an anode chamber, and the eluted metal ions are By passing an electrolytic solution containing ions into the cathode chamber through a neutral membrane and reducing the metal ions in the cathode chamber, the metals supported on the carrier can be eluted and recovered using only a single electrolytic cell. It is characterized by making it possible to perform. Therefore, the circulation line in the conventional electrolysis method is not essential to the present invention, and by appropriately selecting the cathode material, the reduced metal can be precipitated in the cathode chamber without being deposited on the cathode, and the electrolysis can be stopped. It also becomes possible to perform elution and recovery operations continuously without having to do so.

Next, each element constituting the carrier and electrolytic cell in electrolysis according to the present invention will be explained.

The carriers used in the present invention include inorganic carriers such as alumina, silica, and carbon, and organic carriers such as those for ion exchange resins. The metals supported on the carrier and eluted and recovered according to the present invention are not particularly limited, but include metals that have a lower ionization tendency (higher overvoltage) than hydrogen, such as palladium, platinum, gold,
In addition to silver, ruthenium, copper, etc., nickel, which has a high ionization tendency, is used as gold.

These carriers are usually in the form of granules or powder, and in that case, they can be stored as they are in the anode chamber of the electrolytic cell, but for example, in the case of honeycomb-type catalysts, which have been widely used as automobile catalysts in recent years, they can be crushed into a few millimeters. It is desirable to accommodate it in a reasonable size.

The carrier stored in the anode chamber may be stored in a so-called fixed bed state or in a fluidized bed state, but in the case of a fluidized bed state, it may be used after being pulverized more finely.

Further, it is desirable that the carrier is previously subjected to a reduction treatment in order to facilitate metal elution and to remove impurities.

The material of the anode used in the present invention is not particularly limited, and any insoluble anode that is resistant to generated chlorine, such as a dimensionally stable anode (DSA), a carbon (graphite) electrode, or a platinum electrode, can be used.

The material of the cathode used in the present invention is not particularly limited, and any material can be used. However, if the cathode that reduces the metal ions eluted from the carrier is capable of precipitating the reduced metal in the cathode chamber without electrodepositing it on the surface of the cathode, the metal ions deposited on the cathode will be reduced. Since stripping is not necessary, elution and recovery work can be continued continuously without stopping electrolysis. Therefore, as the cathode material, it is preferable to select a material that has a high overvoltage for metal electrodeposition and a low overvoltage for hydrogen generation, that is, a carbon electrode. The reaction on the cathode surface during electrolytic reduction of a solution containing metal ions is a competitive reaction between metal electrodeposition and hydrogen generation, and in order to prevent metal deposition on the cathode surface, metal electrodeposition naturally occurs. This is because it is desirable to almost selectively generate only hydrogen by selecting a material that is difficult (high overvoltage for metal electrodeposition) and easy to generate hydrogen (low overvoltage for hydrogen generation).

Commonly used cathode materials include nickel, iron, stainless steel, etc., as well as materials whose main components are lead, silver, etc., but the former is not suitable because the overvoltage for both metal electrodeposition and hydrogen generation is low. However, the latter is not very suitable because the overvoltage for both metal electrodeposition and hydrogen generation is high.

On the other hand, carbon materials such as graphite and activated carbon that can be preferably used in the present invention have a high overvoltage for metal electrodeposition but a low overvoltage for hydrogen generation, and limit the reaction on the cathode surface only to hydrogen generation. effective in preventing

In order to more effectively inhibit metal electrodeposition on the cathode surface, it is necessary to increase the current density and increase the hydrogen generation rate to prevent the metal to be deposited on the cathode. preferable. Preferably, the current density is 5 A/d+s" or more, more preferably IOA 7 dm" or more, and most preferably 15 A/dm" or more. Although it depends on other electrolytic conditions, at a current density of 15 A/dI11!, the total amount of precipitation is 80
% precipitates in the cathode chamber as metal particles.

In order to construct an electrolytic cell using the above cathode and anode, it is necessary to divide the electrolytic cell into a cathode chamber and an anode chamber using a diaphragm. This is mainly to prevent the carrier housed in the anode chamber from flowing into the cathode chamber and to prevent the metal element reduced in the cathode chamber from flowing back into the anode chamber and being dissolved again. The material of the diaphragm must be capable of preventing the above-mentioned inflow, and must also be able to pass through the electrolytic solution containing the metal ions eluted in the anode chamber, making it a liquid-permeable neutral membrane. Examples of the neutral membrane include filter cloth, clay plate, asbestos sheet, and insulator.

When a relatively low-strength filter cloth or the like is used as the neutral membrane, it is preferable to use, for example, a composite structure in which the filter cloth is reinforced with a vinyl chloride plate and a titanium plate as a sandwich structure.

The structure of an electrolytic cell can be one in which a box-shaped electrolytic cell is divided into left and right halves using the above-mentioned neutral membrane, or a cylindrical electrolytic cell is separated into an outer cathode chamber and an inner one by using a cylindrical neutral membrane. Alternatively, a box-shaped electrolytic cell can be divided into multiple electrolytic chambers using multiple neutral membranes, and the electrodes for each electrolytic chamber can be connected in a bipolar or unipolar manner. Alternatively, the metal may be eluted or reduced in a plurality of electrolytic chambers.

During electrolysis, a means is required to allow the electrolytic solution containing metal ions eluted by chlorinated hydrochloric acid in the anode chamber of the electrolytic cell to permeate through the neutral membrane to the cathode chamber. This can usually be accomplished by adjusting the level of the anolyte and catholyte.

In other words, if the height of the anolyte is always maintained higher than the height of the catholyte, the electrolyte will always permeate through the neutral membrane from the anode chamber to the cathode chamber due to the pressure difference between the two anolytes on the neutral membrane. and there is no backflow.

Preferably, the anolyte level is maintained at the catholyte level by periodically or continuously withdrawing the catholyte to the outside and circulating it into the anolyte chamber.

In particular, as mentioned above, when a carbon electrode is used as the cathode and the metal reduced by the cathode is precipitated in the cathode chamber, the reduced metal must also be recovered by taking out the catholyte and performing separation operations such as filtration. This is more preferable because it allows Further, the catholyte may contain fine residues of the carrier such as alumina, and in this case, it is preferable to separate the residues by filtration or the like and then circulate them to the anode chamber.

In the anode chamber containing the carrier, it is desirable to use an electrolytic solution that is appropriately circulated depending on whether the accommodation method is a fixed bed type or a fluidized bed type. For example, in the case of a fluidized bed, a circulating electrolyte is supplied from below the anode chamber at a relatively high rate in order to fluidize the accommodated carriers, and in the case of a fixed bed, the supported metal is electrolyzed between adjacent carriers. In order to improve contact with the liquid, for example, a circulating electrolyte is supplied from above the anode chamber to the lower part of the anode chamber through a cylindrical supply pipe passed through the fixed bed, and the carrier is slightly fluidized by the rising force of the electrolyte. It is preferable to let

In addition, in order to replace the carrier without stopping electrolysis when most of the metal on the carrier housed in the anode chamber is eluted, an extraction port is provided at the lower end of the anode chamber, and the carrier is taken out from the extraction port. Preferably, the same amount of metal support is added to the anode chamber.

During electrolysis, especially when using a carbon electrode as the cathode and trying to prevent the deposition of the reduced metal onto the cathode,
It is preferable to stir the inside of the cathode chamber.

For example, when elution and recovery of palladium from a catalyst carrier supporting palladium is performed by the method of the present invention having the above-mentioned configuration, palladium on the carrier is first chlorinated with chlorine in chlorine-containing hydrochloric acid and converted to palladium chloride. At the same time, it elutes into the electrolyte and becomes palladium ions. The palladium ions, dissolved in the electrolytic solution, move toward the neutral membrane depending on the pressure difference between the two electrode chambers, pass through the neutral membrane, and reach the cathode chamber. In the cathode chamber, the palladium ions are converted to Pd" + by the generated hydrogen gas or by contact with the cathode according to the following formula:
H, -Pd + 2H" to form metal palladium, which precipitates in the cathode chamber or is deposited on the cathode. Particularly when the cathode chamber is stirred, the growth of the metal particles is observed, but it is relatively slow. Because of its small particle size, it does not cause problems such as clogging or abrasion of pumps, piping, etc. even if it is circulated together with the solution.

According to the method of the present invention described above, metals supported on a carrier can be eluted and recovered almost quantitatively in a single electrolytic cell without using expensive chemicals, and moreover, a carbon electrode is used as a cathode. And by adjusting the cathode current density, it is possible to precipitate all or most of the metal particles into the cathode chamber without depositing them on the cathode. Therefore, in a preferred embodiment of the present invention, the metal supported on the carrier can be eluted and recovered continuously in a single electrolytic cell without using expensive chemicals (and without stopping the electrolytic operation). It becomes possible.

Examples of the present invention will be described below with reference to the accompanying drawings, but the present invention is not limited to these examples.

(Example 1) Vertical 20cI11. Width 33cm, depth 54cm (effective capacity is 20cm x 33cm x 45cm = 29.
The box-shaped electrolytic cell 1 of 71) is divided into three by two liquid-permeable neutral membranes 2 with a vinyl mesh and filter cloth supported from both sides by vinyl chloride plates and titanium plates, and cathode chambers 3 are placed on both sides in the center. Cathode chamber 4
was formed. Each anode chamber 3 has an anode 5 of 55 cm in length.
A total of two graphite plates, one each 20 cm wide and 1 cm thick, were installed in close contact with the wall of the electrolytic cell so that only one side of each graphite plate effectively functioned as an anode, and in the cathode chamber. is the cathode 6, which is 55 cm long;
A graphite plate with a width of 10 cm and a thickness of 1 cm was installed.

A jacket (shown in the figure) for cooling the electrolytic solution was installed around the electrolytic cell, and cooling water was allowed to flow through the jacket to cool the electrolytic solution.

The alumina carrier 7 carrying palladium and platinum in the amounts shown in Table 1 below was housed in the anode chamber 3 of the electrolytic cell 1 in a fixed bed state, and the amount of current, voltage, and total amount of electrolyte were maintained at the values shown in the table. At the same time, an electrolytic solution having a hydrochloric acid concentration of 224 g/l is supplied, and the same amount is extracted from the cathode chamber to the circulation line 8, and the elemental metal contained therein is filtered out by the filter 9 attached to the line 8, and 48.21! An air lift with a diameter of 19 m and a length of 60 cm uses an electrolyte of Air valve 11 installed on the bottom plate of the anode chamber at the lower end of the cylindrical body 10
The carrier in the anode chamber was taken out of the electrolytic cell by supplying compressed air from the anode chamber, and a new carrier was supplied from the upper part of the anode chamber. The amount of anolyte was maintained at 3.81 in each chamber, totaling 7.61, and the amount of catholyte was maintained at 7.81. The anode and cathode current densities and metal concentrations in the electrolyte during energization were as shown in Table 1.

After 330 minutes, the electricity supply was stopped, the metal precipitated on the cathode 6 was collected, the amount of metal precipitated in the cathode chamber and the amount of metal remaining in the electrolyte was measured, and the amount of metal deposited on the cathode chamber was measured. The amount of metal still supported on the sample was measured, the elution rate was calculated, and the results shown in Table 1 were obtained.

Table 1 (Example 2) Using the same apparatus as in Example 1, elution and recovery of each metal from an autocatalyst supporting platinum, palladium, and rhodium according to the conditions listed in the upper column of Example 2 in Table 1. I tried. The results are shown in the lower column of Example 2 in Table 1.

(Example 3) Using the same apparatus as in Example 1, attempts were made to elute and recover each metal from an autocatalyst supporting platinum, palladium, and rhodium according to the conditions listed in the upper column of Example 3 in Table 1. Ta. The results are shown in the lower column of Example 3 in Table 1.

(Example 4) Spent catalyst A with platinum grade (supported amount) of 858 g/t and palladium grade of 108 g/t or platinum grade of 304 g/t and palladium grade of 610 g
/l of waste catalyst B, current flow rate is 200 A, electrolyte temperature is 60°C, electrolyte solution hydrochloric acid concentration is 20 to 35%, starting capacity of waste catalyst is 9.0 kg, and amount of waste catalyst charged and discharged is 2 kg/l.
of platinum and palladium on the spent catalyst with a charging interval of 15 to 30 minutes/time. After discharging and recovering, the recovered platinum and palladium grade, the platinum and palladium grade of the undissolved residue at the end, and the electrolyte acid concentration were measured, and the results shown in Table 2 were obtained. Table 3 shows the results of calculating the elution rate in the electrolytic solution, the cleaning solution, and the recovered metal, and the undissolved rate in the same manner as in Example 1 above.

From the results of Examples 1 to 4, approximately 15 tables of eluted metals were found.
It can be seen that 2% was recovered in the cleaning solution and the remaining 85% precipitated in the cathode chamber or remained in the electrolyte.

(Example 5) Spent catalyst A of Example 4 9. Okg was placed in the electrolytic cell of each of the above examples in a fixed bed state, and electricity was applied for 3.2 hours without replenishing the waste catalyst under the same conditions as in Example 4, and the platinum and palladium concentrations in the electrolyte and the electrolyte were The acid concentration was measured. Subsequently, 2 kg of each waste catalyst was supplied at predetermined time intervals, and the same amount of treated catalyst was extracted from the electrolytic cell, and the platinum and palladium concentrations in the electrolyte and the acid concentration in the electrolyte were measured for 5.5 hours in the same manner. .

Next, the charged catalyst was changed to catalyst B of Example 4, and 2 kg was similarly charged at a predetermined interval at a time, and the same amount was taken out from the electrolytic cell to determine the platinum and palladium concentrations in the electrolyte and the acid concentration of the electrolyte. was measured over about 6 hours. The results are shown in FIG. The upper arrow in FIG. 2 indicates the time of catalyst charging.

(Effects of the Invention) The present invention is capable of forming metal ions by eluting metals on a carrier with chlorine-containing hydrochloric acid generated by electrolysis of hydrochloric acid, by storing the carrier in an anode chamber of an electrolytic cell. , permeate the electrolytic solution containing the eluted metal ions into the cathode chamber through a neutral membrane, reduce the metal ions in the cathode chamber, and precipitate the corresponding metal element in the cathode chamber or on the cathode. I'm trying to collect it.

Therefore, in the present invention, firstly, the metals supported on the carrier can be eluted and recovered using only a single electrolytic cell, which is different from conventional recovery methods that use aqua regia or elute outside the electrolytic cell. Supported metals can be recovered with far less equipment than conventional or recovery equipment.

Second, cost reduction can be achieved because no chemical reduction step is required, and no harmful components that require post-treatment are generated. Moreover, since the chemical is not used, there is no change in the composition of the solution before and after electrolysis, and the catholyte can continue to be circulated as it is to the anode chamber and used as the anolyte.

Thirdly, when the cathode is constituted by a carbon electrode as one aspect of the present invention, the single metal that is reduced and recovered in the cathode chamber is precipitated almost selectively and is not electrodeposited on the cathode, so that the single metal can be recovered. Since it is no longer necessary to stop electrolysis and peel off the metal from the cathode, continuous operation becomes possible, which greatly increases operational efficiency.

Fourth, since electrolysis is used, the reduction reaction continues even when the concentration of metal ions is low, making it possible to precipitate metal ions as metal particles almost quantitatively.

[Brief explanation of the drawing]

FIG. 1 is a schematic vertical cross-sectional view showing one embodiment of a metal recovery device according to the present invention, and FIG. 2 is a graph showing changes over time in the platinum and palladium concentrations and the acid concentration of the electrolytic solution in Example 5. . 1... Electrolytic cell 2... Liquid permeable neutral membrane 3... Cathode chamber 4... Cathode chamber 5... Anode 6... Cathode 7... Carrier 8... Circulation line 9 ... Filter 10 ... Cylindrical body 11 ... Air valve No. 4

Claims (8)

[Claims] (1) A carrier carrying a metal and/or a metal compound is placed in the anode chamber of an electrolytic cell divided into an anode chamber and a cathode chamber by a liquid-permeable neutral membrane, and an electrolytic solution containing hydrochloric acid is placed in the anode chamber. chlorine is electrolytically generated to elute the metal and/or metal compound into the electrolyte as corresponding metal ions, the electrolyte is permeated through the neutral membrane into the cathode chamber, and the cathode is A method for recovering metals supported on a carrier, comprising reducing and precipitating metal elements in a chamber. (2) The recovery method according to claim 1, wherein the cathode is a carbon electrode, and the reduced metal element is precipitated in the cathode chamber. (3) The recovery method according to claim 2, wherein electrolysis is performed at a cathode current density of 5 A/dm^2 or more. (4) The elemental metal precipitated in the cathode chamber is extracted from the cathode chamber along with the electrolyte, and after the elemental metal is separated, the electrolyte is circulated to the anode chamber. Collection method described in section. (5) A carrier carrying a metal and/or metal compound is accommodated, and the metal and/or metal compound is converted into a corresponding metal ion in the electrolyte using chlorine generated by electrolyzing an electrolyte containing hydrochloric acid. an anode chamber for reducing and precipitating metal ions in the electrolytic solution into corresponding metal elements, and a liquid-permeable neutral membrane that partitions the electrolytic cell into the anode chamber and the cathode chamber. and means for permeating an electrolyte in the anode chamber through the neutral membrane into the cathode chamber. (6) The recovery device according to claim 5, wherein the means for permeating the electrolyte into the cathode chamber is a liquid pressure difference between the two electrode chambers. (7) The recovery device according to claim 6, wherein a liquid pressure difference is generated by extracting the electrolyte from the cathode chamber. (8) The recovery device according to claim 6, wherein the electrolytic solution extracted from the cathode chamber is circulated to the anode chamber.