Electrochemical production of metal powder

Abstract

The present invention relates to a method for producing a powder of a metal in an electrolytic cell comprising an anode made of a metal, a cathode and an electrolyte solution, the method comprising: a) dissolution of the anode forming ions of the metal in the electrolyte solution and depositing the metal particles from the electrolyte solution on the cathode, b) transfer 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 comprises (i) an alkane or alkanol sulfonic acid and (ii) a soluble metal salt of the alkane or alkanol sulfonic acid. The present invention also relates to copper or silver powder obtained or obtainable by the method, as well as the use of the alkane or alkanol sulfonic acid in the electrolyte solution for the production of silver or copper powder by electrolytic deposition.

Description

[Technical field]

[0001] The present invention relates to a process for the electrolytic production of metal powders and to the metal powders obtained therefrom. [Background technology]

[0002] Metal powders such as copper powder and silver powder are widely used in various applications, for example in electronic pastes, lubricants, catalysts, pharmaceuticals and biofilters. Electrolytic deposition of metal powders has always been an important industrial method, since this method can result in high-quality metal powders under mild conditions and does not impose high requirements on the starting materials.

[0003] In the conventional method of producing copper powder by electrolytic deposition, an aqueous copper sulfate solution containing sulfuric acid is generally adopted. This method requires specific measures to protect against the release of corrosive sulfuric acid from the electrolyte solution into the environment, especially under high processing temperatures. In the conventional method of producing silver powder by electrolytic deposition, an aqueous silver nitrate electrolyte solution containing nitric acid is generally adopted. This method also has the problem of the release of nitric acid from the electrolyte solution into the environment under high processing temperatures.

[0004] Furthermore, the inventors of the present invention have found that deposition of silver particles on the cathode in conventional methods using silver nitrate electrolyte solutions is accompanied by the rapid growth of dendritic aggregates, especially at the corners of the cathode, which can extend to the anode, thus increasing the risk of short circuits.

[0005] There is also a need for alternative methods of producing copper and silver powders by electrolytic deposition. It is desirable that the methods be capable of providing metal powders having comparable or even improved quality than those obtained from these conventional methods. Summary of the Invention [Problem to be solved by the invention]

[0006] It is an object of the present invention to provide a method for producing copper and / or silver powders without using an electrolyte solution containing any corrosive acid that may be released into the environment under high electrolysis temperatures. It is a further object of the present invention to provide a method for producing copper or silver powders having a desired or even smaller particle size.

[0007] It has now been found that the objects of the present invention can be achieved by using an electrolyte solution comprising a metal sulfonate and a sulfonic acid. [Means for solving the problem]

[0008] Thus, in one aspect, the present invention provides a method for producing a powder of a metal in an electrolytic cell comprising an anode made of a metal, a cathode and an electrolyte solution, comprising: a) dissolution of the anode to form ions of the metal in the electrolyte solution and deposition of metal particles from the electrolyte solution on the cathode; b) migration of metal particles from the cathode into the electrolyte solution; c) Isolation of metal particles from electrolyte solutions and A method comprising: - the metal is copper or silver, the electrolyte solution comprises (i) an alkane- or alkanol-sulfonic acid and (ii) a soluble metal salt of the alkane- or alkanol-sulfonic acid;

[0009] In another aspect, the present invention provides a copper or silver powder obtained or obtainable by the method described herein.

[0010] In a further aspect, the present invention provides the use of an alkane sulfonic acid or an alkanol sulfonic acid in an electrolyte solution for the production of silver or copper powder by electrolytic deposition. [Brief description of the drawings]

[0011] [Figure 1] 1 shows an SEM image of copper powder produced by the method according to the invention, as described in Example 1.1. [Diagram 2]1 shows an SEM image of copper powder produced by a method not according to the present invention, as described in Comparative Example 1.1. [Diagram 3] FIG. 2 shows an SEM image of silver powder produced by the method according to the present invention, as described in Example 2.1. [Figure 4] 2 shows a morphological image of a silver deposit on a cathode produced by a method according to the invention, as described in Example 2.1. [Diagram 5] FIG. 2 shows an SEM image of silver powder produced by a method not according to the present invention, as described in Comparative Example 2.1. [Figure 6] FIG. 2 shows a morphological image of a silver deposit on a cathode produced by a method not according to the invention, as described in Comparative Example 2.1. [Figure 7] 2 shows the particle size D50 of silver powders produced by the methods according to the present invention described in Examples 2.1 to 2.3 and by methods not according to the present invention described in Comparative Examples 2.1 to 2.3. [Figure 8] 2 shows the particle size D90 of silver powders produced by the method according to the invention as described in Examples 2.1 to 2.3 and by methods not according to the invention as described in Comparative Examples 2.1 to 2.3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The present invention will now be described in detail below. It should be understood that the present invention can be embodied in many different ways and should not be construed as being limited to the embodiments set forth herein. Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

[0013] As used herein, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0014] As used herein, the terms "comprise", "comprising", and the like are used interchangeably with "contain", "containing", and the like, and should be interpreted in an open, non-limiting manner. That is, for example, additional components or elements may be present. Expressions such as "consists of" or "consists essentially of" can be included in "comprises", and the like.

[0015] As used herein, the term "aqueous" means that the electrolyte solution comprises a solvent containing at least 50% water. Preferably, at least 75% of the solvent is water, more preferably 90%. The electrolyte solution solvent can be expected to consist essentially of water without any intentionally added organic solvent. Any type of water can be used, but distilled or deionized water is preferentially used.

[0016] In a first aspect, the present invention relates to a method for producing a powder of a metal in an electrolytic cell comprising an anode made of a metal, a cathode and an electrolyte solution, the method comprising the steps of: a) dissolution of the anode to form ions of the metal in the electrolyte solution and deposition of metal particles from the electrolyte solution on the cathode; b) migration of metal particles from the cathode into the electrolyte solution; and c) isolating the metal particles from the electrolyte solution, - the metal is copper or silver, and the electrolyte solution comprises (i) an alkane- or alkanol-sulfonic acid and (ii) a soluble metal salt of the alkane- or alkanol-sulfonic acid;

[0017] As is known, the anode is made from a metal that is deposited on the cathode, thus continuously supplying metal ions to the electrolyte solution during operation of the electrolytic cell. Typically, the anode can be made from a metal having 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 from copper or silver having a purity within the above ranges.

[0018] There are no particular restrictions on the material of the cathode. Cathodes useful for the method according to the invention can be made, for example, from stainless steel or titanium.

[0019] The anode and cathode can be disposed at a distance of 1 cm to 10 cm, preferably 3 cm to 6 cm, for example 3 cm to 5.5 cm.

[0020] The inventors of the present invention have found 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 is effective for producing silver and copper powders under high electrolysis temperatures without the problem of acid release into the environment.

[0021] Alkanesulfonic acids useful as component (i) are 1 ~C 12 -Alkanesulfonic acids, preferably C 1 ~C 6The alkane sulfonic acid may be a monosulfonic acid or a disulfonic acid. Examples of alkane monosulfonic acids include, but are not limited to, 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-dodecanesulfonic acid. Examples of alkane disulfonic acids include, but are not limited to, methane disulfonic acid, 1,1-ethane disulfonic acid, 1,2-ethane disulfonic acid, 1,1-propane disulfonic acid, 1,3-propane disulfonic acid, 1,1-butane disulfonic acid, and 1,4-butane disulfonic acid. One alkane sulfonic acid or any mixture of two or more alkane sulfonic acids may be used in the electrolyte solution in the method according to the present invention.

[0022] Alkanol sulfonic acids useful as component (i) are 2 ~C 12 -Alkanol sulfonic acids, preferably C 2 ~C 6 -Alkanol sulfonic acids, i.e., hydroxy-substituted C 2 ~C 12 -, preferably C 2 ~C 6-alkanesulfonic acid. The hydroxy can be on the terminal or internal carbon of the alkyl chain of the alkanesulfonic acid. Useful alkanolsulfonic acids include, but are not limited to, 2-hydroxy-1-ethanesulfonic acid, 1-hydroxy-2-propanesulfonic acid, 2-hydroxy-1-propanesulfonic acid, 3-hydroxy-1-propanesulfonic acid, 2-hydroxy-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-1-hexanesulfonic acid, 2-hydroxy-1-decanesulfonic acid, and 2-hydroxy-1-dodecanesulfonic acid. One alkanolsulfonic acid or any mixture of two or more alkanolsulfonic acids can be used in the electrolyte solution in the method according to the invention.

[0023] The alkane sulfonic acids and alkanol sulfonic acids may be prepared by any method known in the art or may be commercially available, without particular limitation.

[0024] The alkanesulfonic acid or alkanolsulfonic acid as component (i) may be contained in the electrolyte solution at a concentration in the range of 1 to 200 grams per liter (g / L), particularly 5 to 180 g / L, and preferably 10 to 150 g / L.

[0025] In the present specification, soluble metal salts of alkanesulfonic acids or alkanolsulfonic acids as component (ii) means soluble silver or copper salts of alkanesulfonic acids or alkanolsulfonic acids, which are also referred to below as soluble metal sulfonates.

[0026] The alkane sulfonic acid or alkanol sulfonic acid from which the soluble metal sulfonate is derived may be the same as 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).

[0027] Preferably the soluble metal sulfonate is a soluble silver or copper salt of an alkanesulfonic acid or an alkanolsulfonic acid as component (i).

[0028] For example, the electrolyte solution may contain methanesulfonic acid as component (i) and copper or silver methanesulfonate as component (ii).

[0029] As component (ii), a soluble metal sulfonate may be contained in the electrolyte solution at a concentration, calculated as metal ion, of 1 to 200 g / L of the electrolyte solution, particularly 5 to 150 g / L, preferably 5 to 120 g / L.

[0030] The electrolyte solution can be prepared by any known method, for example, by dissolving a metal (i.e., copper or silver), metal oxide, metal hydroxide, or metal carbonate in a solution of an alkane sulfonic acid or alkanol sulfonic acid as described above to provide a solution having the desired concentrations of metal ions and sulfonic acid.

[0031] The electrolyte solution may optionally contain one or more additives known to be useful in the art, such as gelatin derived from collagen (e.g., animal glue), glucose, urea. Some inorganic additives may also be mentioned, such as cupric chloride, to improve electrical conductivity or to adjust the pH of the electrolyte solution in copper powder production. When present, additives may be included in the electrolyte solution at a concentration of up to 20 g / L, more preferably up to 10 g / L.

[0032] In some embodiments, the present invention provides a method for producing silver powder in an electrolytic cell comprising an anode made from silver, a cathode, and an electrolyte solution, where the electrolyte solution comprises (i) an alkane- or alkanol-sulfonic acid and (ii) a soluble silver alkane- or alkanol-sulfonate salt.

[0033] In those embodiments of the method for producing silver powder, the alkane sulfonic acid or alkanol sulfonic acid as component (i) is preferably included in the electrolyte solution at a concentration ranging from 1 to 50 grams per liter (g / L) of electrolyte solution, particularly from 5 to 30 g / L, preferably from 10 to 20 g / L. Additionally or alternatively, the soluble silver alkane sulfonate or alkanol sulfonate as component (ii) is preferably included in the electrolyte solution at a concentration ranging from 50 to 200 g / L of electrolyte solution, particularly from 60 to 150 g / L, preferably from 80 to 120 g / L, calculated as silver ions.

[0034] In some other embodiments, the present invention provides a method for producing copper powder in an electrolytic cell comprising an anode made from copper, a cathode, and an electrolyte solution, wherein the electrolyte solution comprises (i) an alkane- or alkanol-sulfonic acid and (ii) a soluble copper alkane- or alkanol-sulfonate salt.

[0035] In those embodiments of the method for producing copper powder, the alkane sulfonic acid or alkanol sulfonic acid as component (i) is preferably included in the electrolyte solution at a concentration in the range of 50 to 200 grams per liter (g / L) electrolyte solution, particularly 80 to 200 g / L, preferably 100 to 160 g / L. Additionally or alternatively, the soluble copper alkane sulfonate or alkanol sulfonate as component (ii) is preferably included in the electrolyte solution at a concentration in the range of 1 to 50 g / L electrolyte solution, particularly 5 to 30 g / L, preferably 5 to 15 g / L, calculated as copper ions.

[0036] In step a), the dissolution of the anode and the deposition on the cathode 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 in the range of 20° C. to 70° C., preferably 30° C. to 60° C., more preferably 40° C. to 50° C.

[0037] The electrolyte solution can be pumped during step a) at a flow rate of about 5-20 liters per minute (L / min). The electrolyte solution can be pumped from a reservoir into the electrolytic cell from the top and out the bottom of the electrolytic cell, or can be pumped into the electrolytic cell from the bottom and out the top of the electrolytic cell.

[0038] Step a) is 2 to 20 A / dm for the production of silver powder. 2 (ASD), especially 3~15A / dm 2 , for example 3~10A / dm 2 , 8~15A / dm for copper powder production 2 The current density can be in the range of 100 .mu.m to 100 .mu.m.

[0039] Dissolution of the anode and deposition on the cathode in step a) is 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).

[0040] In step b), the metal particles can be transferred from the cathode into the electrolyte solution by any mechanical means known in the art without any limitation.

[0041] In step c), the electrolyte solution containing the metal particles obtained from step b) is subjected to isolation to obtain a metal powder. Optionally, the isolated meal powder can be further subjected to post-treatment such as washing, drying and / or oxidation prevention treatment. Post-treatment can be carried out by any conventional means. For example, the isolated meal powder can be washed with deionized water, dried under vacuum and reduced under an atmosphere of hydrogen.

[0042] Thus, the method according to the invention comprises the following steps: d) washing the metal particles isolated from step c) preferably with deionized water; e) Vacuum drying, and f) Preventing oxidation of metal particles, preferably by reduction under an atmosphere of hydrogen It may further include.

[0043] In some exemplary embodiments, the present invention provides a method for producing silver powder in an electrolytic cell comprising an anode made from silver, a cathode, and an electrolyte solution, comprising: a) dissolution of the anode forming silver ions in the electrolyte solution and deposition of silver particles from the electrolyte solution on the cathode; b) migration of silver particles from the cathode into the electrolyte solution; c) Isolation of silver particles from the electrolyte solution and A method comprising: Here, the electrolyte solution is: (i) C 1 ~C 6 -alkanesulfonic acid or alkanolsulfonic acid and (ii) soluble silver C 1 ~C 6 -alkanesulfonate or C 1 ~C 6 -Alkanol sulfonates.

[0044] Preferably, in an exemplary embodiment of the method for producing silver powder, the electrolyte solution comprises: (i) a C solution having a concentration in the range of 1 to 50 g / L electrolyte solution; 1 ~C 6 -alkanesulfonic acid or alkanolsulfonic acid, and (ii) soluble silver C at a concentration of 50 to 200 g / L electrolyte solution. 1 ~C 6 -alkanesulfonate or C 1 ~C 6 -Alkanol sulfonates.

[0045] More preferably, in an exemplary embodiment of the method for producing silver powder, the electrolyte solution comprises: (i) a C solution having a concentration ranging from 5 to 30 g / L, preferably from 10 to 20 g / L electrolyte solution; 1 ~C 6 - an alkane sulfonic acid or an alkanol sulfonic acid, and (ii) soluble silver C, calculated as silver ion, at a concentration of 60 to 150 g / L of electrolyte solution. 1 ~C 6 -alkanesulfonate or C 1 ~C 6 -Alkanol sulfonates.

[0046] Most preferably, in an exemplary embodiment of the method for producing silver powder, the electrolyte solution comprises: (i) a C concentration in the range of 5 to 30 g / L, preferably 10 to 20 g / L electrolyte solution; 1 ~C 6 - an alkane sulfonic acid or an alkanol sulfonic acid, and (ii) soluble silver C, calculated as silver ion, at a concentration of 80 to 120 g / L of electrolyte solution. 1 ~C 6 -alkanesulfonate or C 1 ~C 6 -Alkanol sulfonates.

[0047] In any of the exemplary embodiments of the method for producing silver powder, step a) is carried out at a temperature in the range of 40-50°C, preferably 45-50°C.

[0048] In some other embodiments, the present invention provides a method for producing copper powder in an electrolytic cell comprising an anode made of copper, a cathode, and an electrolyte solution. a) dissolution of the anode forming copper ions in the electrolyte solution and deposition of copper particles from the electrolyte solution on the cathode; b) migration of copper particles from the cathode into the electrolyte solution; c) Isolation of copper particles from the electrolyte solution and A method comprising: Here, the electrolyte solution is: (i) C 1 ~C 6 -alkanesulfonic acid or alkanolsulfonic acid and (ii) soluble copper C 1 ~C 6 -alkanesulfonate or C 1 ~C 6 -Alkanol sulfonates.

[0049] Preferably, in an exemplary embodiment of the method for producing copper powder, the electrolyte solution comprises: (i) a C concentration in the range of 50 to 200 g / L electrolyte solution; 1 ~C 6 - an alkane sulfonic acid or an alkanol sulfonic acid, and (ii) soluble silver C at a concentration of 1 to 50 g / L electrolyte solution. 1 ~C6 -alkanesulfonate or C 1 ~C 6 -Alkanol sulfonates.

[0050] More preferably, in an exemplary embodiment of the method for producing copper powder, the electrolyte solution comprises: (i) a C concentration in the range of 80 to 200 g / L, preferably 100 to 160 g / L electrolyte solution; 1 ~C 6 -alkanesulfonic acid or alkanolsulfonic acid, and (ii) soluble silver, calculated as copper ion, at a concentration of 5 to 30 g / L of electrolyte solution. 1 ~C 6 -alkanesulfonate or C 1 ~C 6 -Alkanol sulfonates.

[0051] Most preferably, in an exemplary embodiment of the method for producing copper powder, the electrolyte solution comprises: (i) a C concentration in the range of 80-200 g / L, preferably 100-160 g / L electrolyte solution; 1 ~C 6 -alkanesulfonic acid or alkanolsulfonic acid, and (ii) soluble silver, calculated as copper ion, at a concentration of 5 to 15 g / L of electrolyte solution. 1 ~C 6 -alkanesulfonate or C 1 ~C 6 -Alkanol sulfonates.

[0052] In any of the exemplary embodiments of the method for producing copper powder, step a) is carried out at a temperature in the range of 40-50°C.

[0053] In a second aspect, the present invention provides a copper or silver powder obtained or obtainable by the method according to the invention described herein.

[0054] The copper powder obtained or obtainable by the method according to the invention has a particle size D in the range of 20 to 120 microns (μm), preferably 30 to 100 μm, more preferably 40 to 90 μm, and most preferably 40 to 80 μm. 50has.

[0055] The silver powder obtained or obtainable by the method according to the invention has a particle size D in the range of 100 to 600 microns (μm), preferably 150 to 500 μm, more preferably 200 to 400 μm. 50 Alternatively or additionally, the silver powder obtained or obtainable by the method according to the invention has a particle size D of 200 to 1,000 microns (μm), preferably 400 to 800 μm. 90 has.

[0056] D 50 is the diameter value at which 50% of the total number of particles characterized consists of particles having a diameter smaller than this value, as measured by a particle size laser analyzer.

[0057] D 90 is the diameter at which 90% of the total number of particles characterized consist of particles having a diameter smaller than this value, as measured by a particle size laser analyzer.

[0058] In a third aspect, the present invention provides the use of an alkane sulfonic acid or an alkanol sulfonic acid in an electrolyte solution for the production of silver or copper powder by electrolytic deposition. EXAMPLES

[0059] Description of measurements in the examples: Scanning Electron Microscopy (SEM): Zeiss Supra® 55 manufactured by Carl Zeiss AG. Particle size measurement: Malvern Mastersizer 2000G.

[0060] In each example, the current efficiency (η) was calculated according to the following formula:

number

[0061] Electrical energy consumption (W) was calculated according to the following formula:

number

[0062] Example 1: Preparation of copper powder Example 1.1 Black CuO was dissolved in a dilute aqueous solution of methanesulfonic acid (MSA) to result in a solution containing 12 g / L copper ions and 140 g / L free methanesulfonic acid as the electrolyte solution. The solution was poured into an electrolytic cell and maintained at a temperature of 40° C. A phosphorus copper plate anode and a titanium plate cathode were placed in the electrolytic cell at a distance of 5 cm. Electrochemical deposition was performed at 13 A / dm for 15 min. 2 The 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 deionized water, dried in a vacuum drying oven at a temperature of 60 °C, and then subjected to a reduction treatment by heating to 500 °C in a reducing atmosphere of hydrogen.

[0063] The bath voltage, as measured by a Kocour power supply, is 2.3 V, 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 dendrites were observed by SEM for the copper powder. The copper powder has a particle size D of 79.5 μm. 50 has.

[0064] 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.

[0065] 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.

[0066] Copper powder particle size D 50 is 81.6 μm.

[0067] 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.

[0068] The bath voltage was 2.5 V, the current efficiency (η) was 85.1%, and the electrical energy consumption (W) was 2476 kW·h / t.

[0069] Copper powder particle size D 50 is 89.2 μm.

[0070] 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.

[0071] 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.

[0072] Copper powder particle size D 50is 100.9 μm.

[0073] 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.

[0074] 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.

[0075] Copper powder particle size D 50 is 78.4 μm.

[0076] 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.

[0077] 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.

[0078] Copper powder particle size D 50 is 46.3 μm.

[0079] 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 an electrolytic cell and maintained at a temperature of 25°C. A phosphorus copper plate anode and a titanium plate cathode were placed in the electrolytic cell at a distance of 5 cm. Electrolytic deposition was performed at 13 A / dm for 15 min. 2 The 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 deionized water, dried in a vacuum drying oven at a temperature of 60°C, and then subjected to a reduction treatment by heating to 500°C in a reducing atmosphere of hydrogen.

[0080] The bath voltage, as measured by a Kocour power supply, is 2.3 V, the current efficiency (η) is 79.86%, and the electrical energy consumption (W) is 2428 kW·h / t. Thick dendrites were observed by SEM for the copper powder, as shown in Figure 2.

[0081] The copper powder has a particle size D of 99.3 μm. 50 has.

[0082] Example 2: Preparation of silver powder Example 2.1 Black Ag 2 O was dissolved in a dilute aqueous solution of methanesulfonic acid (MSA) to result in a solution containing 108 g / L silver ions and 15.25 g / L free methanesulfonic acid as the electrolyte solution. The solution was poured into an electrolytic cell and maintained at a temperature of 50°C. A high purity silver plate anode and a stainless steel plate cathode were placed in the electrolytic cell at a distance of 3.5 cm. Electrochemical deposition was performed at 5 A / dm for 15 min. 2 The 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 deionized water, and dried in a vacuum oven at a temperature of 60 °C.

[0083] The bath voltage, as measured by a Kocour power supply, is 1.23 V, the current efficiency (η) is 98%, and the electrical energy consumption (W) is 312 kW·h / t. Granular crystals were observed by SEM for the silver powder, as shown in Figure 3.

[0084] Silver powder particle size D 50 is 328.8 μm, and D 90 is 525.4 μm.

[0085] As shown in FIG. 4, it was observed that silver particles were deposited on the cathode with slow and slight dendritic growth.

[0086] 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.

[0087] The bath voltage is 1.5 V, the current efficiency (η) is 95%, and the electrical energy consumption (W) is 392 kW·h / t.

[0088] Silver powder particle size D 50 is 545.1 μm, and D 90 is 966.9 μm.

[0089] 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.

[0090] The bath voltage is 1.26 V, the current efficiency (η) is 96%, and the electrical energy consumption (W) is 326 kW·h / t.

[0091] Silver powder particle size D 50 is 571.5 μm, and D 90 is 920.1 μm.

[0092] Comparative Example 2.1 Black Ag 2 O to nitric acid (HNO 3 ) to give a solution containing 108 g / L silver ions and 10 g / L free nitric acid as an electrolyte solution. The solution was poured into an electrolytic cell and maintained at a temperature of 25°C. A high purity silver plate anode and a stainless steel plate cathode were placed in the electrolytic cell at a distance of 3.5 cm. The electrolytic deposition was carried out at 5 A / dm for 15 min. 2 The 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 deionized water, and dried in a vacuum oven at a temperature of 60 °C.

[0093] The bath voltage was 1.4 V, the current efficiency (η) was 95.04%, and the electrical energy consumption (W) was 366 kW·h / t. Granular crystals were observed for the silver powder by SEM, as shown in Figure 5. The particle size D of the silver powder 50 is 78.7 μm, and D 90 is 758.6 μm.

[0094] As shown in FIG. 6, it was observed that silver particles were deposited on the cathode with rapid and extreme dendritic growth, especially at the corners of the cathode.

[0095] 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.

[0096] The bath voltage was 1.11 V, the current efficiency (η) was 96%, and the electrical energy consumption (W) was 287 kW·h / t.

[0097] Silver powder particle size D 50 is 395.2 μm, and D 90 is 648.1 μm.

[0098] 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.

[0099] The bath voltage was 1.04 V, the current efficiency (η) was 98%, and the electrical energy consumption (W) was 264 kW·h / t.

[0100] Silver powder particle size D 50 is 340.3 μm, and D 90 is 1167.3 μm.

[0101] As shown in Figures 7 and 8, silver powders produced according to the present invention at temperatures above 40°C have particle sizes at least comparable to those of silver powders conventionally produced in nitric acid electrolyte systems.

Claims

1. 1. A method for producing powders of metals in an electrolytic cell comprising an anode made of a metal, a cathode, and an electrolyte solution, comprising: a) dissolution of an anode to form metal ions in an electrolyte solution and deposition of metal particles from said electrolyte solution on a cathode; b) migration of metal particles from the cathode into the electrolyte solution; c) isolating the metal particles from the electrolyte solution; and In a method comprising: - the metal is copper or silver, - a method wherein the electrolyte solution comprises (i) an alkane- or alkanol-sulfonic acid and (ii) a soluble metal salt of an alkane- or alkanol-sulfonic acid.

2. The alkanesulfonic acid is C １ ~C １２ -alkanesulfonic acids, preferably C １ ~C ６ The method according to claim 1, wherein the alkane sulfonic acid is selected from the group consisting of:

3. The alkanol sulfonic acid is ２ ~C １２ -Alkanol sulfonic acids, preferably C ２ ~C ６ 2. The method of claim 1, wherein the carboxylic acid is selected from the group consisting of: -alkanol sulfonic acids;

4. 3. The method of claim 2, wherein the alkane sulfonic acid is selected from 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, 1-dodecanesulfonic acid, methanedisulfonic acid, 1,1-ethanedisulfonic acid, 1,2-ethanedisulfonic acid, 1,1-propanedisulfonic acid, 1,3-propanedisulfonic acid, 1,1-butanedisulfonic acid, 1,4-butenedisulfonic acid, and any combination thereof.

5. The process according to any one of claims 1 to 4, wherein step a) is carried out at a temperature in the range of from 20°C to 70°C, preferably from 30°C to 60°C, more preferably from 40 to 50°C.

6. 6. The method according to claim 5, wherein 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.

7. 6. The method of claim 5, wherein copper powder is produced and step a) is carried out at a temperature in the range of 40 to 50°C.

8. The method according to any one of claims 1 to 4, further comprising a step of preventing oxidation of the metal particles, preferably a step of reduction under an atmosphere of hydrogen.

9. A copper or silver powder obtained or obtainable by the method according to any one of claims 1 to 4.

10. 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.

11. Use according to claim 10, wherein the alkanesulfonic acid or alkanolsulfonic acid is as defined in any one of claims 2 to 4.

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