KR20240038984A - Electrolytic manufacturing method of metal powder - Google Patents

Abstract

The present invention relates to a method for producing metal powder in an electrolytic cell comprising an anode, a cathode and an electrolyte solution made of metal, comprising: a) anode dissolution to form ions of the metal in the electrolyte solution and cathodic deposition of metal particles from the electrolyte solution; b) removal of the metal particles from the cathode into the electrolyte solution, and c) isolation of the metal particles from the electrolyte solution, wherein the metal is copper or silver and the electrolyte solution is comprised of (i) an alkane sulfonic acid or an alkanol. A sulfonic acid and (ii) a soluble metal salt of an alkane sulfonic acid or alkanol sulfonic acid. The invention also relates to the copper or silver powder obtained or obtainable by the above process and to the use of alkane sulfonic acids or alkanol sulfonic acids in electrolyte solutions for the production of silver or copper powder by electrolytic deposition.

Description

Electrolytic manufacturing method of metal powder

The present invention relates to a method for electrolytic production of metal powder and a metal powder obtained therefrom.

Fine metal powders such as copper powder and silver powder are widely used in various applications such as electronic pastes, lubricants, catalysts, pharmaceuticals, and biofilters. Electrolytic deposition of metal powders has always been an important industrial process because the process can provide high quality metal powders under mild conditions and does not impose high requirements on starting materials.

In conventional processes for producing copper powder by electrolytic deposition, an aqueous solution of copper sulfate containing sulfuric acid is generally employed. The process requires specific measures to protect against corrosive sulfuric acid emissions from the electrolyte solution into the surrounding environment, especially under elevated process temperatures. In conventional processes for producing silver powder by electrolytic deposition, an aqueous silver nitrate electrolyte solution containing nitric acid is generally employed. The process also suffers from nitric acid emissions from the electrolyte solution into the surrounding environment under elevated process temperatures.

Additionally, the inventors have discovered that in conventional processes using silver nitrate electrolyte solutions, dendritic aggregates grow rapidly as silver particles are deposited on the cathode, especially at the corners of the cathode. Dendritic aggregates can extend to the anode, thereby increasing the risk of short circuiting.

There is still a need for alternative processes for producing copper and silver powders by electrolytic deposition. It is desirable that the process can provide metal powders with quality comparable or even improved to that obtained from conventional processes.

The object of the present invention is to provide a method for producing copper powder and/or silver powder without using an electrolyte solution containing any corrosive acids that may be released into the surrounding environment under elevated electrolysis temperatures. A further object of the present invention is to provide a process for producing copper or silver powders with desirable or even smaller particle sizes.

It has been found that the object of the present invention can be achieved by using an electrolyte solution comprising a metal sulfonate and a sulfonic acid.

Accordingly, in one aspect, the present invention provides a method for producing metal powder in an electrolytic cell comprising an anode, a cathode, and an electrolyte solution made of metal, comprising:

a) anode dissolution to form ions of the metal in the electrolyte solution and cathodic deposition of metal particles from the electrolyte solution,

b) removal of metal particles from the cathode to the electrolyte solution, and

c) isolation of metal particles from the electrolyte solution,

Including,

here,

- The metal is copper or silver,

- An electrolyte solution comprising (i) an alkane sulfonic acid or alkanol sulfonic acid and (ii) a soluble metal salt of an alkane sulfonic acid or alkanol sulfonic acid.

In another aspect, the invention provides copper or silver powder obtained or obtainable by a method as described herein.

In a further aspect, the invention provides the use of an alkane sulfonic acid or alkanol sulfonic acid in an electrolyte solution for the production of silver or copper powder by electrolytic deposition.

Figure 1 shows an SEM image of a copper powder prepared by the method according to the invention, as described in Example 1.1.
Figure 2 shows an SEM image of copper powder prepared by a method not according to the invention, as described in Comparative Example 1.1.
Figure 3 shows an SEM image of silver powder prepared by the method according to the invention, as described in Example 2.1.
Figure 4 shows a photograph of the morphology of a silver deposit on a cathode prepared by the method according to the invention, as described in Example 2.1.
Figure 5 shows an SEM image of silver powder prepared by a method not according to the invention, as described in Comparative Example 2.1.
Figure 6 shows a photograph of the morphology of a silver deposit on a cathode prepared by a method not according to the invention, as described in Comparative Example 2.1.
Figure 7 shows the particle size D ₅₀ of silver powders produced by a process according to the invention described in Examples 2.1 to 2.3 and by a method not according to the invention described in Comparative Examples 2.1 to 2.3.
Figure 8 shows the particle size D ₉₀ of silver powder produced by a process according to the invention described in Examples 2.1 to 2.3 and by a process other than according to the invention described in Comparative Examples 2.1 to 2.3.

Hereinafter, the present invention will be described in detail. It is understood that the invention can be implemented in many different ways and should not be construed as limited to the embodiments disclosed herein. Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by a person skilled in the art to which the present invention pertains.

As used herein, the singular forms “a”, “an” and “the” include plural referents unless the context clearly dictates otherwise.

As used herein, the terms "comprise", "comprising", etc. are used interchangeably with "contains", "containing", etc., and are to be interpreted in a non-limiting, open-ended manner. That is, additional ingredients or elements may be present, for example. The expressions “consisting of” or “consisting essentially of” or cognates may be included within “comprise” or cognates.

As used herein, the term “aqueous” means that the electrolyte solution comprises a solvent comprising at least 50% water. Preferably, at least 75% of the solvent is water, more preferably at least 90%. The electrolyte solution may be considered to consist essentially of water without any intentionally added organic solvents. Any type of water may be used, with distilled or deionized water being preferred.

In one aspect, the present invention provides a method for producing metal powder in an electrolytic cell comprising an anode, a cathode, and an electrolyte solution made of metal, comprising:

a) anode dissolution to form ions of the metal in the electrolyte solution and cathodic deposition of metal particles from the electrolyte solution,

b) removal of metal particles from the cathode to the electrolyte solution, and

c) isolation of metal particles from the electrolyte solution,

Including,

here,

- The metal is copper or silver,

- An electrolyte solution comprising (i) an alkane sulfonic acid or alkanol sulfonic acid and (ii) a soluble metal salt of an alkane sulfonic acid or alkanol sulfonic acid.

As is well known, the anode is made of a metal that is deposited on the cathode to continuously supply metal ions into the electrolyte solution during operation of the electrolytic cell. Generally, the anode may be made of a metal with a purity of at least 95%, for example at least 98% or at least 99%. In the method according to the invention, the anode is made of copper or silver with a purity within the above range.

There are no particular restrictions on the material of the cathode. Cathodes useful in the process according to the invention may be made of stainless steel or titanium, for example.

The anode and cathode may be arranged at a spacing of 1 cm to 10 cm, preferably 3 cm to 6 cm, for example 3 cm to 5.5 cm.

The inventors of the present invention have discovered that an electrolyte solution comprising (i) an alkane sulfonic acid or alkanol sulfonic acid and (ii) a soluble metal salt of an alkane sulfonic acid or alkanol sulfonic acid can be used to transfer silver and copper powders to the surrounding environment under elevated electrolysis temperatures. It was found to be effective in producing without problems with acid release.

Alkane sulfonic acids useful as component (i) may be C ₁ -C ₁₂ -alkane sulfonic acids, preferably C ₁ -C ₆ -alkane sulfonic acids. Alkane sulfonic acids can be monosulfonic acids and disulfonic acids. Examples of alkane monosulfonic acids include methanesulfonic acid, 1-ethanesulfonic acid, 1-propanesulfonic acid, 2-propanesulfonic acid, 1-butanesulfonic acid, 2-butanesulfonic acid, 1-pentanesulfonic acid, 1-hexanesulfonic acid, 1-decanesulfonic acid, and 1-decanesulfonic acid. -Includes, but is not limited to, dodecane sulfonic acid. Examples of alkane disulfonic acids include methanedisulfonic acid, 1,1-ethanedisulfonic acid, 1,2-ethanedisulfonic acid, 1,1-propanedisulfonic acid, 1,3-propanedisulfonic acid, 1,1-butanedisulfonic acid, and Including, but not limited to, 1,4-butanedisulfonic acid. One alkane sulfonic acid or any mixture of two or more alkane sulfonic acids can be used in the electrolyte solution in the process according to the invention.

Alkanol sulfonic acids useful as component (i) are C ₂ -C ₁₂ -alkanol sulfonic acids, preferably C ₂ -C ₆ -alkanol sulfonic acids, i.e. hydroxy substituted C ₂ -C ₁₂ -, preferably C It may be a ₂ -C ₆ -alkane sulfonic acid. The hydroxy can be on a terminal or internal carbon of the alkyl chain of the alkane sulfonic acid. Examples of useful alkanol sulfonic acids include 2-hydroxy-1-ethanesulfonic acid, 1-hydroxy-2-propanesulfonic acid, 2-hydroxy-1-propanesulfonic acid, 3-hydroxy-1-propanesulfonic acid, 2-hydroxy-1-propanesulfonic acid. Roxy-1-butanesulfonic acid, 4-hydroxy-1-butanesulfonic acid, 4-hydroxy-2-butanesulfonic acid, 2-hydroxy-1-pentanesulfonic acid, 4-hydroxy-1-pentanesulfonic acid, 2-hydroxy Includes, but is not limited to, hydroxy-1-hexanesulfonic acid, 2-hydroxy-1-decanesulfonic acid, and 2-hydroxy-1-dodecanesulfonic acid. One alkanol sulfonic acid or any mixture of two or more alkanol sulfonic acids can be used in the electrolyte solution in the process according to the invention.

Alkane sulfonic acids and alkanol sulfonic acids may be prepared by any method known in the art or commercially available without particular limitation.

The alkane sulfonic acids and alkanol sulfonic acids as component (i) are present in the electrolyte solution in an amount ranging from 1 to 200 grams per liter (g/L) of electrolyte solution, especially from 5 to 180 g/L, preferably from 10 to 150 g/L. It can be included in concentration.

Here, soluble metal salt of an alkane sulfonic acid or alkanol sulfonic acid as component (ii) means a soluble silver or copper salt of an alkane sulfonic acid or alkanol sulfonic acid. Soluble silver or copper salts of alkane sulfonic acids or alkanol sulfonic acids will also be referred to hereinafter as soluble metal sulfonates.

The alkane sulfonic acid or alkanol sulfonic acid from which the soluble metal sulfonate is derived may be the same or different from the alkane sulfonic acid or alkanol sulfonic acid as component (i) and may be selected from those described above for component (i).

Preferably, the soluble metal sulfonate is a soluble silver or copper salt of an alkane sulfonic acid or alkanol sulfonic acid as component (i).

For example, the electrolyte solution may include methanesulfonic acid as component (i) and copper or silver methanesulfonate as component (ii).

The soluble metal sulfonate as component (ii) will be included in the electrolyte solution at a concentration of 1 to 200 g/L of electrolyte solution, especially 5 to 150 g/L, preferably 5 to 120 g/L, calculated in terms of metal ions. You can.

The electrolyte solution may be prepared by any known method, for example, by mixing a metal (i.e., copper or silver), an oxide of a metal, a hydroxide of a metal, or a carbonate of a metal with an alkane sulfonic acid or alkane as described hereinabove. Dissolution in a solution of all-sulfonic acid provides a solution with the desired concentration of metal ion and sulfonic acid.

The electrolyte solution may optionally include one or more additives known to be useful in the art, such as gelatin derived from collagen (e.g., animal glue), glucose, urea. In copper powder production, some inorganic additives, for example copper chloride, may also be mentioned to adjust the pH of the electrolyte solution or improve the electrical conductivity. Additives, if present, may be included in the electrolyte solution at a concentration of 20 g/L or less, more preferably 10 g/L or less.

In some embodiments, the present invention provides a method of making silver powder in an electrolyte cell comprising an anode, a cathode, and an electrolyte solution made of silver, wherein the electrolyte solution comprises (i) an alkane sulfonic acid or an alkanol sulfonic acid and (ii) Soluble includes alkane sulfonates or alkanol sulfonates.

In these embodiments of the method for producing silver powder, the alkane sulfonic acid and alkanol sulfonic acid as component (i) are present in the electrolyte solution in an amount of 1 to 50 grams per liter (g/L) of the electrolyte solution, especially 5 to 30 g/L, Preferably it is included in a concentration ranging from 10 to 20 g/L. Additionally or alternatively, the soluble silver alkane metal or alkanol sulfonate as component (ii) is preferably present in the electrolyte solution at 50 to 200 g/L of electrolyte solution, especially 60 to 150 g/L, calculated as silver ions. , preferably at a concentration of 80 to 120 g/L.

In some other embodiments, the present invention provides a method of making copper powder in an electrolyte cell comprising an anode, a cathode, and an electrolyte solution made of copper, wherein the electrolyte solution comprises (i) an alkane sulfonic acid or an alkanol sulfonic acid and (ii) ) soluble copper alkane sulfonate or alkanol sulfonate.

In these embodiments of the method for producing copper powder, the alkane sulfonic acid and alkanol sulfonic acid as component (i) are present in the electrolyte solution in an amount of 50 to 200 grams per liter (g/L) of the electrolyte solution, especially 80 to 200 g/L, Preferably it is included in a concentration ranging from 100 to 160 g/L. Additionally or alternatively, the soluble copper alkane metal or alkanol sulfonate as component (ii) is preferably present in the electrolyte solution at 1 to 50 g/L of electrolyte solution, especially 5 to 30 g/L, calculated in terms of copper ions. , preferably at a concentration of 5 to 15 g/L.

In step a), the anode dissolution and cathode deposition can be carried out at ambient temperature or at elevated temperature, depending on the temperature of the electrolyte solution. For example, the method can be carried out at a temperature ranging from 20 to 70°C, preferably from 30 to 60°C, more preferably from 40 to 50°C.

The electrolyte solution may be pumped during step a) at a flow rate of about 5 to 20 liters per minute (L/min). The electrolyte solution may be pumped from a reservoir into the electrolytic cell from the top and discharged from the bottom of the electrolytic cell, or may be pumped into the electrolytic cell from the bottom and discharged from the top of the electrolytic cell.

Step a) is carried out at 2 to 20 A/dm ² (ASD), especially 3 to 15 A/dm ² , for example 3 to 10 A/dm ² for the production of silver powder and 8 to 15 A/dm 2 for the production of copper powder. It can be performed with current densities in the range dm ² .

The anode dissolution and cathode deposition in step a) are generally carried out for a period of 10 to 60 minutes, for example 10 to 30 minutes, before removing the metal particles deposited on the cathode in step b).

In step b), the metal particles can be removed from the cathode into the electrolyte solution by any mechanical means known in the art without any restrictions.

In step c), the electrolyte solution containing the metal particles obtained from step b) is isolated to provide a metal powder. Optionally, the isolated metal powder may be further subjected to post-processing including washing, drying and/or anti-oxidation treatment. Post-processing may be performed by any conventional means. For example, the isolated metal powder can be washed with deionized water, dried under vacuum and reduced under a hydrogen atmosphere.

Accordingly, the method according to the invention may further comprise the following steps:

d) washing of the metal particles isolated from step c), preferably with deionized water,

e) vacuum drying step, and

f) Prevention of oxidation of metal particles, preferably a reduction step under a hydrogen atmosphere.

In some exemplary embodiments, the present invention provides a method for producing silver powder in an electrolytic cell comprising an anode, a cathode, and an electrolyte solution made of silver, comprising:

a) anode dissolution to form silver ions in the electrolyte solution and cathode deposition of silver particles from the electrolyte solution,

b) removal of silver particles from the cathode to the electrolyte solution, and

c) Isolation of silver particles from electrolyte solution

Including,

wherein the electrolyte solution comprises (i) a C ₁ -C ₆ -alkane sulfonic acid or alkanol sulfonic acid and (ii) a soluble silver C ₁ -C ₆ -alkane sulfonate or C ₁ -C ₆ -alkanol sulfonate. provides.

Preferably, in an exemplary embodiment of the method for preparing silver powder, the electrolyte solution comprises (i) C ₁ -C ₆ -alkane sulfonic acid or alkanol sulfonic acid at a concentration ranging from 1 to 50 g/L of electrolyte solution, and ( ii) Soluble at a concentration of 50 to 200 g/L of electrolyte solution comprises C ₁ -C ₆ -alkane sulfonate or C ₁ -C ₆ -alkanol sulfonate.

More preferably, in an exemplary embodiment of the method for preparing silver powder, the electrolyte solution has (i) C ₁ - at a concentration ranging from 5 to 30 g/L of electrolyte solution, preferably from 10 to 20 g/L. C ₆ -alkane sulfonic acid or alkanol sulfonic acid, and (ii) the solubility of the concentration of 60 to 150 g/L of electrolyte solution, calculated as silver ions, of C ₁ -C ₆ -alkane sulfonate or C ₁ -C ₆ - Contains alkanol sulfonates.

Most preferably, in an exemplary embodiment of the method for preparing silver powder, the electrolyte solution has (i) C ₁ - at a concentration ranging from 5 to 30 g/L of electrolyte solution, preferably from 10 to 20 g/L. C ₆ -alkane sulfonic acid or alkanol sulfonic acid, and (ii) the solubility of the concentration of 80 to 120 g/L of electrolyte solution, calculated as silver ions, of C ₁ -C ₆ -alkane sulfonate or C ₁ -C ₆ - Contains alkanol sulfonates.

In any of the exemplary embodiments of the method for preparing silver powder, step a) is carried out at a temperature in the range of 40 to 50° C., preferably 45 to 50° C.

In some other embodiments, the present invention provides a method for producing copper powder in an electrolytic cell comprising an anode, a cathode, and an electrolyte solution made of copper, comprising:

a) anode dissolution to form copper ions in the electrolyte solution and cathode deposition of copper particles from the electrolyte solution,

b) removal of copper particles from the cathode to the electrolyte solution, and

c) isolation of copper particles from the electrolyte solution,

Including,

wherein the electrolyte solution comprises (i) C ₁ -C ₆ -alkane sulfonic acid or alkanol sulfonic acid and (ii) soluble copper C ₁ -C ₆ -alkane sulfonate or C ₁ -C ₆ -alkanol sulfonate. provides.

Preferably, in an exemplary embodiment of the method for preparing copper powder, the electrolyte solution contains (i) a C ₁ -C ₆ -alkane sulfonic acid or alkanol sulfonic acid at a concentration ranging from 50 to 200 g/L of electrolyte solution, and ( ii) Soluble concentrations of 1 to 50 g/L of electrolyte solution include C ₁ -C ₆ -alkane sulfonates or C ₁ -C ₆ -alkanol sulfonates.

More preferably, in an exemplary embodiment of the method for preparing copper powder, the electrolyte solution has (i) C ₁ - at a concentration in the range of 80 to 200 g/L of electrolyte solution, preferably in the range of 100 to 160 g/L. The solubility of the C ₆ -alkane sulfonic acid or alkanol sulfonic acid, and (ii) the concentration of 5 to 30 g/L of electrolyte solution, calculated as copper ions, is the C ₁ -C ₆ -alkane sulfonate or C ₁ -C ₆ - Contains alkanol sulfonates.

Most preferably, in an exemplary embodiment of the method for preparing copper powder, the electrolyte solution has (i) C ₁ - at a concentration in the range of 80 to 200 g/L of electrolyte solution, preferably in the range of 100 to 160 g/L. The solubility of the C ₆ -alkane sulfonic acid or alkanol sulfonic acid, and (ii) the concentration of 5 to 15 g/L of electrolyte solution, calculated as copper ions, is the C ₁ -C ₆ -alkane sulfonate or C ₁ -C ₆ - Contains alkanol sulfonates.

In any of the exemplary embodiments of the method for producing copper powder, step a) is carried out at a temperature ranging from 40 to 50° C.

In a second aspect, the invention provides copper or silver powder obtained or obtainable by the process according to the invention as described herein.

The copper powder obtained or obtainable by the process according to the invention has a particle size in the range of 20 to 120 microns (μm), preferably 30 to 100 μm, more preferably 40 to 90 μm, most preferably 40 to 80 μm. It has a particle size of D ₅₀ .

The silver powder obtained or obtainable by the process according to the invention has a particle size D ₅₀ in the range of 100 to 600 microns (μm), preferably 150 to 500 μm, more preferably 200 to 400 μm. Additionally or alternatively, the silver powder obtained or obtainable by the process according to the invention has a particle size D ₉₀ in the range of 200 to 1,000 microns (μm), preferably 400 to 800 μm.

D ₅₀ is the diameter value in which 50% of the total number of characterized particles consists of particles having a diameter smaller than this value, as determined by a particle size laser analyzer.

D ₉₀ is the diameter in which 90% of the total number of characterized particles consist of particles having a diameter smaller than this value, as measured by a particle size laser analyzer.

In a third aspect, the invention provides the use of alkane sulfonic acids or alkanol sulfonic acids in electrolyte solutions for the production of silver or copper powder by electrolytic deposition.

Example

Description of measurements in the examples:

Scanning electron microscopy (SEM): Zeiss Supra® 55 (Carl Zeiss AG).

Particle size measurement: Malvern Mastersizer 2000G.

In each example, the current efficiency (η) was calculated according to the following equation:

During the ceremony,

η represents the current efficiency, expressed in %;

m represents the mass of metal powder deposited per cell over a period of t, expressed in g;

I represents the current intensity and is expressed as A;

t represents the electroplating period, expressed in time;

q represents the electrochemical equivalent weight of the metal, which is 1.186 g/(A·h) for copper and 4.025 g/(A·h) for silver.

Electrical energy consumption (W) was calculated according to the following equation:

During the ceremony,

W represents energy consumption, expressed in kW·h/t;

η represents the current efficiency, expressed in %;

U represents the average bath voltage and is expressed as V.

Example 1 Preparation of copper powder

Example 1.1

Black CuO was dissolved in an aqueous solution of dilute methanesulfonic acid (MSA) to provide a solution containing 12 g/L of copper ions and 140 g/L of free methanesulfonic acid as the electrolyte solution. The solution was poured into the electrolytic cell and maintained at a temperature of 40°C. In the electrolytic cell, the anode of the phosphor copper plate and the cathode of the titanium plate were placed at 5 cm intervals. Electrolytic deposition was carried out by applying direct current at a current density of 13 A/dm ² for 15 minutes. The obtained copper particles were then removed from the cathode and isolated from the electrolyte solution. The collected copper particles were filtered by vacuum filtration, washed with DI water, dried in a vacuum drying oven at a temperature of 60°C, and then subjected to reduction treatment by heating to 500°C in a reducing atmosphere of hydrogen.

The bath voltage is 2.3 V as determined by Kocour power supply, the current efficiency (η) is 89.32% and the electrical energy consumption (W) is 2171 kW·h/t. As shown in Figure 1, sparse and thin dendritic crystals were observed through SEM for the copper powder. The copper powder has a particle size D ₅₀ of 79.5 μm.

Example 1.2

The process was carried out in the same manner as described in Example 1.1, except that the electrolyte solution was maintained at a temperature of 25°C.

The bath voltage is 2.8 V, the current efficiency (η) is 82.7%, and the electrical energy consumption (W) is 2854 kW·h/t.

The particle size D ₅₀ of the copper powder is 81.6 μm.

Example 1.3

The process was carried out in the same manner as described in Example 1.1, except that the electrolyte solution was maintained at a temperature of 30°C.

The bath voltage is 2.5 V, the current efficiency (η) is 85.1%, and the electrical energy consumption (W) is 2476 kW·h/t.

The particle size D ₅₀ of the copper powder is 89.2 μm.

Example 1.4

The process was carried out in the same manner as described in Example 1.1, except that the electrolyte solution was maintained at a temperature of 35°C.

The bath voltage is 2.6 V, the current efficiency (η) is 87.8%, and the electrical energy consumption (W) is 2496 kW·h/t.

The particle size D ₅₀ of the copper powder is 100.9 μm.

Example 1.5

The process was carried out in the same manner as described in Example 1.1, except that the electrolyte solution was maintained at a temperature of 45°C.

The bath voltage is 2.35 V, the current efficiency (η) is 89.16%, and the electrical energy consumption (W) is 2222 kW·h/t.

The particle size D ₅₀ of the copper powder is 78.4 μm.

Example 1.6

The process was carried out in the same manner as described in Example 1.1, except that the electrolyte solution was maintained at a temperature of 50°C.

The bath voltage is 2.2 V, the current efficiency (η) is 91.53%, and the electrical energy consumption (W) is 2026 kW·h/t.

The particle size D ₅₀ of the copper powder is 46.3 μm.

Comparative Example 1.1

Copper sulfate pentahydrate was dissolved in an aqueous sulfuric acid solution to obtain a solution containing 12 g/L of copper ions and 142 g/L of free sulfuric acid as an electrolyte solution. The solution was poured into the electrolytic cell and maintained at a temperature of 25°C. In the electrolytic cell, the anode of the phosphor copper plate and the cathode of the titanium plate were placed at 5 cm intervals. Electrolytic deposition was carried out by applying direct current at a current density of 13 A/dm ² for 15 minutes. The obtained copper particles were then removed from the cathode and isolated from the electrolyte solution. The collected copper particles were filtered by vacuum filtration, washed with DI water, dried in a vacuum drying oven at a temperature of 60°C, and then subjected to reduction treatment by heating to 500°C in a reducing atmosphere of hydrogen.

The bath voltage is 2.3 V as determined by Kocour power supply, the current efficiency (η) is 79.86% and the electrical energy consumption (W) is 2428 kW·h/t. As shown in Figure 2, thick dendritic crystals were observed through SEM for the copper powder.

The copper powder has a particle size D ₅₀ of 99.3 μm.

Example 2 Preparation of silver powder

Example 2.1

Black Ag ₂ O was dissolved in an aqueous solution of dilute methanesulfonic acid (MSA) to provide a solution containing 108 g/L of silver ions and 15.25 g/L of free methanesulfonic acid as the electrolyte solution. The solution was poured into the electrolytic cell and maintained at a temperature of 50°C. In the electrolytic cell, the anode of pure silver plate and the cathode of stainless steel plate were placed at 3.5 cm intervals. Electrolytic deposition was performed by applying direct current at a current density of 5 A/dm ² for 15 minutes. The obtained silver particles were then removed from the cathode and isolated from the electrolyte solution. The collected silver particles were filtered by vacuum filtration, washed with DI water, and dried in a vacuum drying oven at a temperature of 60°C.

The bath voltage is 1.23 V, as determined by Kocour power supply, the current efficiency (η) is 98% and the electrical energy consumption (W) is 312 kW·h/t. As shown in Figure 3, granular crystals were observed through SEM for the silver powder.

The particle size D ₅₀ of the silver powder is 328.8 μm, and D ₉₀ is 525.4 μm.

As shown in Figure 4, silver particles were observed to deposit on the cathode slowly and with little dendritic growth.

Example 2.2

The process was carried out in the same manner as described in Example 2.1, except that the electrolyte solution was maintained at a temperature of 25°C.

The bath voltage is 1.5 V, the current efficiency (η) is 95%, and the electrical energy consumption (W) is 392 kW·h/t.

The particle size D ₅₀ of the silver powder is 545.1 μm, and D ₉₀ is 966.9 μm.

Example 2.3

The process was carried out in the same manner as described in Example 2.1, except that the electrolyte solution was maintained at a temperature of 40°C.

The bath voltage is 1.26 V, the current efficiency (η) is 96%, and the electrical energy consumption (W) is 326 kW·h/t.

The particle size D ₅₀ of the silver powder is 571.5 μm, and D ₉₀ is 920.1 μm.

Comparative Example 2.1

Black Ag ₂ O was dissolved in an aqueous solution of dilute nitric acid (HNO ₃ ) to provide a solution containing 108 g/L of silver ions and 10 g/L of free nitric acid as the electrolyte solution. The solution was poured into the electrolytic cell and maintained at a temperature of 25°C. In the electrolytic cell, the anode of pure silver plate and the cathode of stainless steel plate were placed at 3.5 cm intervals. Electrolytic deposition was performed by applying direct current at a current density of 5 A/dm ² for 15 minutes. The obtained silver particles were then removed from the cathode and isolated from the electrolyte solution. The collected silver particles were filtered by vacuum filtration, washed with DI water, and dried in a vacuum drying oven at a temperature of 60°C.

The bath voltage is 1.4V, the current efficiency (η) is 95.04%, and the electrical energy consumption (W) is 366 kW·h/t. As shown in Figure 5, granular crystals were observed through SEM for the silver powder. The particle size D ₅₀ of the silver powder is 78.7 μm, and D ₉₀ is 758.6 μm.

As shown in Figure 6, silver particles were observed to deposit on the cathode with rapid and rigorous dendritic growth, especially at the corners of the cathode.

Comparative Example 2.2

The process was carried out in the same manner as described in Comparative Example 2.1, except that the electrolyte solution was maintained at a temperature of 40°C.

The bath voltage is 1.11V, the current efficiency (η) is 96%, and the electrical energy consumption (W) is 287 kW·h/t.

The particle size D ₅₀ of the silver powder is 395.2 μm, and D ₉₀ is 648.1 μm.

Comparative Example 2.3

The process was carried out in the same manner as described in Comparative Example 2.1, except that the electrolyte solution was maintained at a temperature of 50°C.

The bath voltage is 1.04V, the current efficiency (η) is 98%, and the electrical energy consumption (W) is 264 kW·h/t.

The particle size D ₅₀ of the silver powder is 340.3 μm, and D ₉₀ is 1167.3 μm.

As shown in Figures 7 and 8, the silver powder produced according to the present invention has a particle size at least comparable to that of silver powder produced with a conventional nitric acid electrolyte system at temperatures above 40°C.

Claims (11)

A method for producing metal powder in an electrolytic cell comprising an anode, a cathode, and an electrolyte solution made of metal, comprising:
a) anode dissolution to form ions of the metal in the electrolyte solution and cathodic deposition of metal particles from the electrolyte solution,
b) removal of metal particles from the cathode to the electrolyte solution, and
c) isolation of metal particles from electrolyte solution
Including,
here,
- The metal is copper or silver,
- A method of preparing the electrolyte solution comprising (i) an alkane sulfonic acid or alkanol sulfonic acid and (ii) a soluble metal salt of an alkane sulfonic acid or alkanol sulfonic acid. The process according to claim 1, wherein the alkane sulfonic acid is selected from C ₁ -C ₁₂ -alkane sulfonic acids, preferably C ₁ -C ₆ -alkane sulfonic acids. The process according to claim 1, wherein the alkanol sulfonic acid is selected from C ₂ -C ₁₂ -alkanol sulfonic acids, preferably C ₂ -C ₆ -alkanol sulfonic acids. The method of claim 2, wherein the alkane sulfonic acid is methanesulfonic acid, 1-ethanesulfonic acid, 1-propanesulfonic acid, 2-propanesulfonic acid, 1-butanesulfonic acid, 2-butanesulfonic acid, 1-pentanesulfonic acid, 1-hexanesulfonic acid, and 1-decane. Sulfonic acid, 1-dodecanesulfonic acid, methanedisulfonic acid, 1,1-ethanedisulfonic acid, 1,2-ethanedisulfonic acid, 1,1-propanedisulfonic acid, 1,3-propanedisulfonic acid, 1,1-butanedi A method of preparation selected from sulfonic acid, 1,4-butenedisulfonic acid, and any combinations thereof. The process according to any one of claims 1 to 4, wherein step a) is carried out at a temperature in the range from 20°C to 70°C, preferably from 30°C to 60°C, more preferably from 40°C to 50°C. . 6. Process according to claim 5, wherein the silver powder is produced and step a) is carried out at a temperature in the range of 40 to 50° C., preferably 45 to 50° C. 6. Process according to claim 5, wherein copper powder is produced and step a) is carried out at a temperature in the range of 40 to 50° C. The production method according to any one of claims 1 to 7, further comprising a step of preventing oxidation of the metal particles, preferably a reduction step under a hydrogen atmosphere. Copper or silver powder obtained or obtainable by the process according to any one of claims 1 to 8. Use of alkane sulfonic acids or alkanol sulfonic acids in electrolyte solutions for the production of silver or copper powders by electrolytic deposition. Use according to claim 10, wherein the alkane sulfonic acid or alkanol sulfonic acid is as defined in any one of claims 2 to 4.