KR20120115999A - Method and arrangement for producing metal powder - Google Patents

Abstract

A method and apparatus for producing metal powders. In this method, the dissolved yield metal is mixed in a solution containing at least one intermediate metal to precipitate the dissolved utility metal into the yield metal powder 14. In the process, the first portion of the acid-containing starting solution is supplied as an anolyte (1) to the anode side (6) of the electrolysis cell in contact with a feed material comprising the anode and the yielding metal, which also comprises the intermediate metal. A second portion of the acid-containing starting solution is supplied to the cathode side 8 of the electrolysis cell, so as to be in contact with the cathode 4 as the catholyte 3; The yield metal is oxidized and dissolved in the anolyte 1 by directing an electric current to the anode 2; The yield metal contained in the second portion of the starting solution is reduced at the cathode side 8; The anolyte solution and catholyte solution are then supplied to the precipitation chamber 12 to mix the second portion of the starting solution comprising the dissolved and oxidized yield metal and the reduced intermediate metal.

Description

METHOD AND ARRANGEMENT FOR PRODUCING METAL POWDER

The present invention relates to the production of finely divided metal powders. In particular, the present invention relates to dissolution-precipitation methods and apparatuses for producing metal powders.

In general, in many metal fabrication processes the end product is a plate-shaped object in the form of a cathode. Final products of this kind are obtained, for example, by a pyrometallurgical production route using electrolysis. In these methods, metal anodes made of concentrate by dry metallurgy can be smelted to cathode copper by electrolysis, which can be cast, for example, into a variety of other types of products. Methods of this type can be used in particular to produce copper, nickel or cobalt products.

However, in the manufacture of metals, in many cases, for example for further processing, it would be advantageous if the metals received as the final product of the manufacturing process were obtained in some other form than a uniform solid object such as a cathode plate. In particular, methods in which the final product is obtained as pure metal powder will be very useful.

In patent application JP 2002327289, a method for producing copper powder by electrolysis is introduced. In this method, an aqueous sulfuric acid solution containing a titanium cathode is directed to the anode chamber whereby the titanium cathodes reduce the dissolved copper in the anode chamber, which precipitates into finely divided copper powder in the anode chamber. The problem with this method is that the catholyte solution is guided directly to the anode chamber, so that the mixing ratio of the catholyte solution and the anolyte solution cannot be controlled effectively. In addition, in this method copper precipitates directly into the anode chamber, which makes it more difficult to remove the deposited copper from the electrolysis device. These problems have the risk of forming copper aggregates that make the particle size control of the copper powder more difficult.

Patent publication US 2005/0023151 introduces a method in which copper powder is made by depositing copper from copper sulfate at the cathode by electrolysis. This method uses a ferrous / ferric anode reaction, whereby the energy consumption of the method is reduced. The publication also describes a through-flow arrangement in which the precipitated copper powder is recovered from the electrodes by an electrolyte flowing through the electrodes. A disadvantage of the methods and apparatus illustrated in the publication US 2005/0023151 is that the recovery of copper from the cathode is not reliable, in particular due to the deposition of copper and the attachment of copper to the cathode, for example at various other locations in the chamber including the electrodes. . Because of the above disadvantages, in particular, it is difficult to control the grain size of the copper powder and the morphoogy of the copper particles as well as to achieve homogeneous quality with the separated electrodes. In addition, the precipitation of copper directly on the cathode is also determined by the cathode material and surface morphology, which in part increases the unreliability of the method.

Patent application WO 2008/017731 introduces a method for producing a metal powder. In this method, the valuable metal powder is precipitated by reducing the valuable metal dissolved by the method by another metal. In this method also the dissolution of the precious metal occurs in the reaction with the other metal, which not only controls the process kinetics but also weakens its efficiency and significantly complicates the methods and apparatus used here.

It is an object of the present invention to eliminate the aforementioned disadvantages of the prior art and to propose a new method and apparatus for producing metal powders by solution-precipitation methods using electrolysis.

The method according to the invention is characterized by what is given in independent claim 1.

The device according to the invention is characterized by what is presented in independent claim 20.

In the process according to the invention for producing metal powder, the dissolved yield metal is mixed with a solution comprising at least one intermediate metal to precipitate the dissolved yield metal into the yield metal powder. In this method, the first portion of the acid-containing starting solution is moved to the anode side of the electrolysis cell as anolyte to contact the feed material including the anode and the yielding metal and, in addition to the acid, the acid-containing starting solution comprising the intermediate metal as well. The second portion of is moved to the cathode side of the electrolysis cell as the catholyte to contact the cathode; The breakdown metal is oxidized and dissolved in the anolyte by conducting current to the anode; The intermediate metal included in the second portion of the starting solution is reduced at the cathode side; The anolyte solution and the catholyte solution are then transferred to the precipitation chamber to mix a second portion of the starting solution comprising an oxidized yield metal and a reduced intermediate metal dissolved in the first portion of the starting solution.

The apparatus according to the present invention is an apparatus for producing a metal powder by mixing a dissolved yield metal powder with a solution containing at least one intermediate metal to precipitate the yield metal powder. The apparatus according to the invention comprises an electrolysis cell for dissolving the yield metal located on the anode side of the electrolysis cell and oxidizing it in the anolyte and reducing the dissolved intermediate metal located on the cathode side of the electrolysis cell on the cathode side; A precipitation chamber disposed essentially separate from the electrolysis cell; And an anolyte solution and a catholyte solution from the anode side and the cathode side of the electrolysis cell to mix the catholyte solution containing the reduced intermediate metal and the oxidized yield metal dissolved in the anolyte outside the electrolysis cell. Means for supplying each of the.

Among the advantages of the present invention, one can point out, for example, good controllability of the particle size of the precipitated yield metal powder, which is possible in particular by supplying anolyte and catholyte solutions to be mixed together in separate precipitation chambers. In this case, the mixing ratio of the solutions can be easily and accurately controlled as well as optimized according to the process conditions. Moreover, when carrying out the precipitation step in a separate precipitation chamber spaced near the electrodes, the effects of the electrodes on the precipitation process and the precipitation collection can be minimized, thereby improving the reliability of the process. In addition, the recovery of the yield metal precipitates becomes easier and more reliable. With the correct mixing ratio and effective precipitate recovery, the formation of yield metal aggregates in the precipitation step can be prevented, so that the homogeneity of the yield metal particles contained in the powder becomes possible for the size of these yield metal particles. The correct mixing ratio also has better efficiency and facilitates the process, which can be used to reduce the amount of energy required for the process to produce any amount of yield metal mass.

Unless otherwise stated, the terms "anode side" and "cathode side" in this document refer to the part of the electrolysis cell that contains the anolyte or catholyte near the anode or cathode, respectively. The "anode side" or "cathode side" need not be a constant part of the electrolysis cell, but the "anode side" or "cathode side" is a number of mutually separated elements comprising an anode or a cathode and an anolyte or catholyte respectively. It may consist of

Unless otherwise stated, the term "diaphragm" in this document refers to any suitable film or thin mechanical obstacle, such as membranes, industrial fabrics, and the like.

Unless otherwise stated, the term "oxidation state", "oxidation level" or corresponding term in this document refers to the charge level at which valences are evident either alone or in the molecule. Thus, the term "oxidation state", "oxidation level" or the corresponding term may also refer to an apparent atomic charge.

In one embodiment of the invention, the first portion of the starting solution comprises a mediating metal for increasing the dissolution of the yield metal at the anode side. In one embodiment of the present invention, the first portion of the circulating solution prepared as a result of mixing the anolyte solution and the catholyte solution is returned to the anolyte solution. In one embodiment of the invention, the first portion of the starting solution consists of the first portion of the circulating solution. Further, in one embodiment of the present invention, the second portion of the circulating solution resulting from mixing the anolyte solution and the catholyte solution is returned to the catholyte. Furthermore, in one embodiment of the present invention, the second portion of the starting solution consists of the second portion of the circulating solution. Moreover, in one embodiment of the invention, the circulating solution essentially returns completely to the electrolyte, in which case the circulating solution consists essentially of the first portion of the circulating solution and the second portion of the circulating solution. When the anolyte solution formed from the first portion of the starting solution and the catholyte solution formed from the second portion of the starting solution are mixed together, the yield metal oxidized and dissolved in the anolyte is reduced and the intermediate metal reduced in the catholyte is oxidized. As a result, yield metal powder is produced. The resulting circulating solution is recycled in the apparatus for use in the process of one of the embodiments of the invention so that the circulating solution is partially or completely anolyte and / or after the mixing step and after the yield metal precipitate has been separated from the solution. Return to the catholyte. The medium metal is now reduced again in the catholyte. Thus, electrolytic regeneration of the mediating metal in the catholyte can be realized, which means that in some embodiments of the invention, there is essentially no need to supply a fresh solution containing the mediating metal to the process. In addition, in some embodiments of the present invention, when the anolyte also comprises a mediator metal, the mediator metal enhances dissolution of the yield metal at these process conditions, for example with a relatively low acid-containing content, wherein Dissolution with the combined effect of the current and acidic solution would not be effective.

In one embodiment of the invention, the anolyte and catholyte are mechanically separated by an electrically conductive diaphragm. In one embodiment of the present invention, the electrolysis cell comprises an electrically conductive diaphragm provided between the anode side and the cathode side of the electrolysis cell to mechanically separate the anode side and the cathode side.

Further, in one embodiment of the present invention, the electrically conductive separator solution is guided between two diaphragms separating the anolyte and the catholyte to prevent premature mixing of the anolyte and the catholyte. In one embodiment of the present invention, an electrolysis cell is provided between the anode side and the cathode side of the electrolysis cell to mechanically separate the anode side and the cathode side by an electrically conductive separator solution disposed in the space between the two diaphragms. Two electrically conductive diaphragms.

In order to realize this step essentially completely so that the precipitation step can be efficiently separated from the electrolysis cell and controlled in a separate deposition chamber, the anolyte and catholyte can be separated by an electrically conductive diaphragm. Can be. In this document, the term "electrically conductive diaphragm" refers to a diaphragm that is electrically conductive such that the diaphragm facilitates the effective operation of the electrolysis cell. However, in some embodiments of the present invention, the electrical conductivity of the diaphragm may be lower than the electrical conductivity of solutions mechanically separated by the diaphragm. As a result, the use of the diaphragm is to mechanically separate the solution located on the other sides of the diaphragm, ie to serve as a mechanical obstacle, while at the same time being electrically conductive so that the electrolysis cell can function effectively. This diaphragm divides the electrolysis cell into an anode portion (or anode side) where the anolyte solution is located and a cathode portion (or cathode side) where the catholyte solution is located. Thus, the anolyte and catholyte cannot be mixed together without disturbing the anode and cathode reactions, and the metal powder cannot be formed near the electrodes in the electrolysis cell. To further enhance the separation of the anode and the cathode, two partition diaphragms may be used between the anode side and the cathode side, and a separator solution may be supplied between the diaphragms.

In one embodiment of the invention, the yield metal is copper. In one embodiment of the invention, the yield metal is selected from the following group: nickel, cobalt, zinc, silver, gold, ruthenium, rhodium, palladium, osmium, iridium, platinum, manganese, zirconium, tin, cadmium and indium.

In one embodiment of the invention, the mediating metal is vanadium. Further, in one embodiment of the present invention, the mediating metal is selected from the following group, titanium, chromium and iron. Further, in one embodiment of the present invention, the mediating metal is selected from the following group: manganese, zirconium, molybdenum, technetium, tungsten, mercury, germanium, arsenic, selenium, tin, antimony, tellurium and copper. In various embodiments of the present invention, the yield metal and the intermediate metal can be selected from the group determined by various other process parameters, in particular the pH value (ie, oxygen content) of the electrolyte. Based on this description of the present invention, one of ordinary skill in the art can find suitable mediation metals for any yield metal by routine tests in the group listed above. In particular, it has been found that, for example, copper powder can be produced efficiently and reliably in one embodiment of the present invention when the chosen intermediate metal is vanadium.

In one embodiment of the invention, the feed material comprising the yield metal is disposed at the anode. Further, in one embodiment of the present invention, the yield metal located on the anode side of the electrolysis cell is disposed at the anode of the electrolysis cell. When the feed material comprising the yield metal is placed at the anode, the rate per unit time of the current passing through the yield metal and consequently also the yield metal dissolved mass per unit time can be controlled efficiently. An advantage of this embodiment is the precise control of the dissolution reaction, in particular by electricity; Yield metals dissolve exactly according to Faraday's laws, depending on the amount of electricity used for a given period. Moreover, the rate of reaction in the dissolution step is rapid since the amount of yield metal dissolved in the anolyte is directly proportional to the charge flowing through the anode. Thus, the amount of yield metal dissolved in the anolyte can also be controlled efficiently and accurately, which facilitates more accurate control of process mechanics and improved reliability.

In one embodiment of the invention, the yield metal is selected such that the selected yield metal is dissolved in the anolyte as a soluble salt of the acid contained in the first portion of the starting solution.

In one embodiment of the present invention, the electrolyte is placed in an oxygen free environment so as to prevent oxidation of the yield metal and / or the intermediate metal contained in the electrolyte. This makes it easier to control the oxygen content of the electrolyte, which occurs in other solutions of the process and the balance of chemical reactions, including for example yield metals and / or intermediate metals, can be more precisely controlled, as a result in particular It means improving the reliability and efficiency of the process.

In one embodiment of the invention, the starting solution comprises sulfuric acid. Furthermore, in one embodiment of the invention, the sulfuric acid content of the starting solution is at least 50 g / l, and preferably in the range of 50 g / l to 1500 g / l. In one embodiment of the invention, the starting solution comprises hydrochloric acid or nitric acid. Further, in one embodiment of the present invention, the hydrochloric acid content in the starting solution is in the range of 15 g / L to 500 g / L. In another embodiment of the invention, the starting solution comprises alkaline chloride in addition to hydrochloric acid, the content of which in the starting solution is in the range of 15 g / L to 500 g / L. The suitability of the acid in the starting solution is, in particular, determined by the feed material, the yield metal and the mediator metal in question. In some embodiments of the invention, the solutions may also include more than one acid. Based on this detailed description of the present invention, one of ordinary skill in the art can know, by routine tests, suitable acids for any feed materials, yielding metals and intermediate metals and suitable contents of such acids. In particular, in some embodiments of the present invention, it has been found that when the intermediate metal is vanadium, the sulfuric acid content of the starting solution at least 50 g / L provides for efficient oxidation of the copper anode and its dissolution at the anode. Suitable acids and the content of these acids should be chosen so that the yield metal dissolves from the feed material into the anolyte, instead of the oxidation of the intermediate metal. Therefore, the anolyte pH (ie oxygen content) must be appropriate. When the yield metal used is copper and the intermediate metal is vanadium, the oxygen content should be as high as possible.

In one embodiment of the invention, the electrolysis cell comprises at least one bag defined by the diaphragm to limit the anolyte and / or catholyte inside the bag. In addition, in one embodiment of the invention, the electrolysis cell comprises means for guiding the separator solution from the space left between the two diaphragms to the anode side and / or the cathode side.

The above-described embodiments of the present invention can be freely combined with each other. Various other embodiments can be combined to create a new embodiment. The method or apparatus to which the present invention relates may comprise one or several of the foregoing embodiments of the present invention.

In the following specification, the invention is described with reference to the accompanying drawings.

1 is a flow diagram illustrating one embodiment of a method according to the invention.
2 is a schematic diagram of one embodiment of a device according to the invention.
3 is a schematic block diagram illustrating an embodiment of the method according to the invention.
4 is a schematic diagram of one embodiment of an electrolysis cell in an apparatus according to the invention.
5 shows scanning electron microscope images (SEM images) of copper powder prepared by one embodiment of the present invention.

For simplicity, the reference numerals for the various elements of the present invention remain the same with respect to the corresponding repeated elements.

In the preparation step S1 of the embodiment of the method according to FIG. 1, both the anode side and the cathode side of the electrolysis cell are prepared and supplied with an acid-containing starting solution, an electrolyte solution, which has a high potential value (ie more High oxidation state). In this method it is essential that at least the second part of the starting solution supplied to the cathode side contain the medium metal at a high potential value, because in step S2, a low potential value in the catholyte (ie, a lower oxidation state) This is because the reduction of the intermediate metal, that is, the regeneration of the intermediate metal, is performed. In addition, the first part of the starting solution, ie, the part supplied as the anolyte solution, may contain the intermediate metal at a high potential value. In some embodiments of the invention, the starting solution may comprise two or even several other mediating metals. In some embodiments of the invention, the first and second portions of the starting solution are identical in composition. By this process, the possibility of changing the composition of the electrolytes after starting the process is minimized, which means that the operating point of the process is stabilized more quickly and the controllability of the process is improved.

The type of intermediate metal suitable for this process is essentially determined by the yield metal chosen, which must be dissolved in the anolyte in step S2 and later precipitated as a powder in mixing step S3. The intermediate metal and the selected yield metal together define other features of the starting solution suitable for this method, in particular the acid contained in this solution, and the content of said acid in this solution.

For example, in prevailing process conditions, the pH value of the solution should be determined so that, on the anode side, the oxidation of the yield metal and its dissolution in the anolyte is more advantageously performed than the oxidation of the intermediate metal in the anolyte. This kind of process conditions, ie functional windows, can be found for many different pairs of yield metals and intermediate metals. In view of the description of the present invention as well as Pourbaix diagrams of various other intermediary metals and yielding metals, finding these functional windows represents routine testing to those skilled in the art.

Starting solutions can be prepared in many different ways, which are determined, in particular, by means of a suitable intermediate metal. One method is to dissolve, for example, in an aqueous solution of a suitable acid, oxide containing the desired intermediate metal. If necessary, the acid-containing content of the starting solution and the oxidized water of the dissolved intermediate metal can then be adjusted to suit the starting solution. Oxidation water control of the intermediate metal can be carried out, for example, by electrolysis.

When the starting solution is formed in step S1, it is supplied as an electrolyte in an electrolysis cell in which the feed material containing the yield metal is located on the anode side. In the method according to FIG. 1, after step (1), the yield metal in step (2) dissolves on the anode side of the electrolysis cell from the feed material to the anolyte as the yield metal is oxidized at the same time and starts on the cathode side. The medium metal in the solution is reduced from a high potential value to a low potential value. In particular, in consideration of manufacturing, it is advantageous that the content of the intermediate metal and the content of the yielding metal dissolved in the solution are as high as possible. Thus, any solution volume provides more precipitated yield metal powder in the mixing step S3 than in the state where the content of the intermediate metal and / or dissolved yield metal in the solution is low.

The process according to FIG. 1 can be realized by the apparatus schematically shown in FIG. 2, wherein the feed material used here is present as anode 2, which is provided for a fast reaction rate upon dissolution of the yield metal, Dissolution of the feed material is directly proportional to the charge flowing to the anode 2. Dissolution reactions can now be controlled particularly accurately by using electricity; In a given period, a large amount of yield metal dissolved and oxidized at the anode is exactly proportional to the amount of electricity used according to Faraday's law. Respectively, equimolar amounts of the intermediate metal are regenerated (reduced) at the cathode. The apparatus of FIG. 2 also includes a cathode 4, an anode side 6 of the electrolysis cell, a cathode side 8, an anolyte filtration equipment 10, a precipitation chamber 12, a separator equipment 16, and a circulating solution. Cleaning equipment 18 for use. The anolyte 1 and the catholyte 3 are mechanically separated by an electrically conductive separator solution 5 disposed in the intermediate space 11 and two electrically conductive diaphragms 7 defining the intermediate space. The aim is to ensure that the yield metal cations generated at the anode side and the intermediate metal which are reduced to a low potential value at the cathode side do not contact each other in the electrolysis cell. Thus, the yield metal powder cannot be precipitated directly at the anode or cathode side of the electrolysis cell, which, if it occurs, can weaken the controllability of the process as well as for example the particle size of the yield metal powder as well as the process efficiency In addition, the recovery of the yield metal powder will be more difficult. In order to improve the separation of the anolyte 1 and the catholyte 3, the separator solution 5 provided in the intermediate space 11 is also maintained at a higher fluid static pressure than the anolyte 1 and the catholyte 3. Can be.

After step S2, in step S3, the anolyte solution is guided at the anode side of the electrolysis cell and the catholyte solution is guided from its cathode side, for example in suitable pipes or in other ways. Guided into the precipitation chamber 12 at a suitable ratio spaced apart in the vicinity of (2, 4). Since the anolyte solution and catholyte solution are guided to the separate precipitation chamber 12, the mixing ratio of the solutions can be easily and accurately controlled, which can be optimized according to the process conditions. With accurate mixing ratio and efficient precipitate recovery, formation of yield metal aggregates in the precipitation step can be prevented, and as a result homogeneity to the size of the yield metal particles contained in the yield metal powder 14 is ensured. The correct mixing ratio also has better efficiency and facilitates the process, which in turn reduces the amount of energy required for the process to produce any amount of yield metal mass.

In the precipitation chamber 12, the anolyte solution and the catholyte solution guided to the chamber 12 can be mixed or continuously mixed. Prior to guiding the anolyte solution into the precipitation chamber 12, and also in some embodiments of the present invention anolyte filtration equipment 10 suitable for this use, the metal foreign matter and / or other possible foreign matter which interferes with the yield metal precipitation process. Can be removed from As a result of the mixing process, the reduced metal in the catholyte solution is oxidized back to its high potential value while the oxidized yield metal of the anolyte solution is reduced and precipitated as a solid yield metal powder 14. From the obtained circulating solution, the yield metal is separated in step S4 by, for example, centrifuging the circulating solution in a separator equipment 16 suitable for this use.

When the yield metal powder 14 is recovered, the resulting circulating solution is recycled to the electrolysis cell in step S5, part of which is circulated to the anolyte 1 and part to the catholyte 3. Before circulating the circulating solution back to the electrolysis cell, any dissolved yield metal as well as any remaining metal particles that may remain in the circulating solution are removed in a cleaning equipment 18 suitable for this use. The cleaning operation may be carried out by reduction and filtration, for example by electrolysis. In order to improve process efficiency and control of the particle size of the yield metal powder, thorough removal of the yield metal consisting of both dissolution and precipitation from the circulating solution before recycling the circulating solution back to the electrolysis cell is useful for the reliability of the process.

In the above-described method, the composition of the circulating solution is essentially the same as that of the starting solution, because when precipitated, the intermediate metal is oxidized back to its starting solution value and the yielding metal dissolved in the anolyte (1) on the anode side. Precipitates and separates from the silver solution. Thus, the circulating solution produced in this method can be reused as a starting solution. If recycling of the circulating solution back to the anolyte and the catholyte is also carried out in the same proportion as was applied when the corresponding electrolyte was supplied to the precipitation chamber at the anode side and the cathode side in step S3, the essentially closed electrolyte circulation is It can be used in the process without the need to separately add / remove the solution to or from the anode side 6 or the cathode side 8 of the electrolysis cell.

In practice, the method of FIG. 1 is generally realized by continuous electrolyte circulation, as a result of which the yielding metal contained in the feed material (anode 2) is electrolyzed until the recycling of the electrolyte solution (circulating electrolyte) stops in the apparatus. When completely dissolved in the cell, the yield metal powder 14 separated and recovered into the circulating solution subsequently accumulates in the precipitation chamber 12. When it is no longer necessary to produce the yield metal powder 14, or when the yield metal of the feed material is finished at the anode side 6 of the electrolysis cell, the recovered yield metal powder 14 is subjected to step S6. Processing is terminated, and the process is stopped. In other preferred embodiments of the present invention, the finishing treatment for the recovered yield metal powder 14 is carried out by the in-process process of separating the yield metal powder 14 and feeding it to the finishing treatment equipment (not shown). Can be performed simultaneously with other steps.

In the embodiment according to FIG. 3, shown in a block diagram, the intermediate metal used is vanadium, which is a high potential value of V ^{3 +} cation. The yield metal used is copper, which is disposed in the feed material serving as the anode 2. From a solution containing a vanadium intermediate metal V ^{3 +} cations, for example a vanadium oxide (V ₂ O ₃₎ for example, it can be prepared by dissolving in sulfuric acid solution. When including V ^{3 +} cations in solution and be a sulfuric acid content of the solution, for example, the starting solution is in a range of 50 g / ℓ ~ 1,500 g / ℓ to form, its first portion as an anode solution 1 It is supplied to the anode side 6 of the electrolysis cell, and the second part is supplied to the cathode side 8 as the catholyte 3. When flowing a current through the electrolysis cell, V ^{3 +} cations are reduced to V ^{2 +} cations in the cathode mixture (3) on the cathode side 8, a copper anode as the oxidized Cu ^{2 +} cations from the anode (2) It dissolves in the liquid (1). As a result, the anode reaction is ^{Cu 0 -> Cu 2 + 2e} - and the cathode reaction is V ³⁺ + e ^{- -> 2 +} V a.

In dissolving copper and oxidizing copper in the anolyte (1), in some embodiments of the present invention the intermediate metal may be involved in the corresponding reactions, for example with such a low acid content at these process conditions Both dissolution and oxidation would be improved, where dissolution and oxidation would only be inefficient with the combined effect of current and acid solution. Now, the exact mechanism of how the intermediate metal is involved in the dissolution and oxidation of the yield metal is determined by the selected yield metal and the intermediate metal. In the above embodiment, when the yield metal is copper and the intermediate metal is vanadium, the vanadium may be oxidized to a mediated oxidation state (V ^{5 +} ) much higher than the V ^{3 +} state on the anode side 6, after which V ^{5 +} hayeoseo is reacted with copper and the copper oxide is dissolved. Now, the "over-oxidized" vanadium (V ^{5 +} ) is reduced back to its original high potential value (V ^{3 +} ). On the anode side 6, "peroxide" corresponding to the intermediate oxidation state is also possible with vanadium and other intermediate metals.

Then, the anolyte solution and the catholyte solution have a suitable ratio in the precipitation chamber 12 in which copper is precipitated through the reaction 2V ^{2 +} + Cu ^{2 +} -> 2V ^{3 +} + Cu ⁰ at a ratio of, for example, 1: 3. Guided and mixed in proportions. In order to be on the basis of the precipitation reaction, involved in all the V ^{2 +} Cu ^{2 +} cations are precipitated in the copper present in the solution, the anolyte and catholyte are in theory the mixing ratio 1: require two. The optimum mixing ratio is determined not only by the reaction state and current efficiency of the anode reaction, but also by the reaction state and current efficiency of the cathode reaction.

For the efficiency and reliability of the process, any significant amount of V ^{2 +} and / or Cu ^{2 +} cation is useful to ensure that the solution remains in the circulation. Some embodiments in the form of, for example, all the Cu ^{2 +} cation is advantageous to try to be consumed in the deposition reaction and to ensure the actual mixing ratio of the anolyte and catholyte in this case of the present invention is from 1: may be a N, Where N> 2. However, the parameter (N) value also depends on how the circulating solution is cleaned before feeding back to the electrolysis cell. Based on the description of the present invention, finding a suitable mixing ratio is a routine test apparent to those skilled in the art.

When copper is precipitated into powder 14 and separated from the remaining solution by separator equipment 16, the remaining circulating solution is any copper, solid copper and dissolved and unprecipitated Cu that may remain in solution in the separation process. ^{It is} cleaned in the cleaning equipment 18 having ^{2 +} cations. The washing can be carried out, for example, by precipitation and filtration by electrolysis. After the chemical and mechanical cleaning, the remaining circulating solution is essentially the same composition as the starting solution containing vanadium cation (V ^{3 +} ) and sulfuric acid in the aqueous solution as a result of the precipitation reaction. This circulating solution is further divided into the anolyte 1 on the anode side 6 and the catholyte 3 on the cathode side 8 at a suitable ratio. After the regeneration described above, the same circulating electrolyte can be guided back through the apparatus and method for precipitating more / fresh copper powder 14 into the precipitation chamber 12.

The solid yielding metal powder 14 separated from the solution is finished in the finishing treatment apparatus (FIG. 1, step S6). Separation and finishing treatment processes can include many different steps depending on the nature of the final product desired. In some embodiments of the invention, the yield metal powder 14 separated from the circulating electrolyte is washed with water to minimize impurities carried together from the solution, after which the yield metal powder 14 is dried and in particular of powder It is coated with a passivation layer to prevent oxidation. In order to minimize the re-dissolution of the precipitated yield metal powder 14 back into the circulating solution, it is useful to carry out the separation of the yield metal powder 14 from the circulating electrolyte by the separator equipment 16, and possible after the precipitation reaction. It is good to carry out the wash as soon as possible.

In some embodiments of the invention, the yield metal powder 14 is subjected to various separate washing operations. Between washing operations, the yield metal powder 14 is separated from the washing liquid. In one embodiment of the present invention, the yield metal powder 14 obtained in the separator equipment 16 and separated from the circulating electrolyte by centrifugation, but still wet, has a mass mixing ratio of 1:20 (one part of wet yield metal powder). 14 and 20 parts of water). Between mixing operations, the yield metal powder 14 is separated from the wash liquor.

The exact construction and operation of the cleaning equipment can even vary greatly, and producing such equipment is apparent to those skilled in the art in light of the description of the present invention. In a preferred embodiment of the invention, the cleaning equipment for realizing several continuous cleaning operations can be, for example, a conveyor belt type device, wherein the wet yielding metal powder 14 is a conveyor for carrying the yielding metal powder 14 into the cleaning liquid. Poured onto the belt, where the yield metal powder is then poured on the conveyor belt or the like. Precipitation of the yield metal powder 14 now occurs when the yield metal powder is separated from the wash liquid, that is, when the wash liquid containing the yield metal powder is poured onto the conveyor belt.

In addition to the embodiments described above, or instead of the procedures described herein, the isolated yield metal powder can of course also be washed by many known methods, for example siphon.

Various other electrolysis cell structures can be designed to dissolve and oxidize the yield metal at the anode side of the electrolysis cell and to reduce the intermediate metal at the cathode side of the electrolysis cell. The electrolysis cell structure shown schematically in FIG. 4 can be used in the apparatus to produce the yield metal powder 14 in an efficient and reliable and efficient manner.

In the electrolysis cell of FIG. 4, the anode side 6 and the cathode side 8 comprise several sections, namely diaphragm bags, defined by the diaphragm 7. Each diaphragm bag comprises an anode 2 or a cathode and an anolyte 1 or a catholyte 3 respectively. Of course, the anode 2 and the cathode 4 are connected to a power source (not shown). Between each diaphragm bag, an electrically conductive separator solution 5 is supplied, which in one embodiment of the invention comprises the intermediate metal in an appropriate high potential value, ie in an oxidized state; In the case of the embodiment described above, the separator solution 5 may for example comprise V ^{3 +} ions.

In addition, the electrolysis cell of FIG. 4 has a supply pipe 9 for supplying the separator solution to the intermediate space 11 left between the diaphragm bags, the overflow channel 13 for the separator solution 4, the anolyte solution and As well as the drainage channels 15 for the catholyte solution, as well as the protective film 17. The electrolysis cell of FIG. 4 can be connected to another device, for example the precipitation chamber 12 (not shown in FIG. 4) via the drainage channels 15 and the supply pipe 9.

In the embodiment of the present invention, the separator solution 5 serves as the starting solution, in which case the composition of the separator solution 5 is the same as the composition of the starting solution. The starting solution can now be supplied to the intermediate space 11 of the electrolysis cell shown in FIG. 4 through the holes provided in the feed pipe 9. From the intermediate space 11, the separator solution 5 flows into the diaphragm bags as the anolyte 1 and the catholyte 3 through the perforations provided in the diaphragms 7. Additionally or alternatively, the diaphragm may be semipermeable such that the separator solution 5 (starting solution) may be controlled in flow through the diaphragm 7 as the anolyte 1 and / or the catholyte 3. Approach Anode reactions and cathode reactions occur in diaphragm bags as described above. The resulting catholyte solution comprising the reduced medium metal as well as the anolyte solution comprising the dissolved or oxidized yield metal can be led to the precipitation chamber 12 via the outlets 15, for example. In some embodiments of the invention, the outlets 15 can serve as an overflow channel for removing excess electrolyte from the device, in which case the anolyte solution and / or catholyte solution is for example It may be moved to the precipitation chamber 12 by another route through suction inlets provided for this purpose. The circulating solution, which in turn is produced in the precipitation chamber 12, after possible cleaning steps, for example through the feed pipe 9, back into the intermediate space 11 and further anolyte 1 and / or catholyte ( 3) can be recycled.

By adjusting the permeability of the diaphragms 7 or the size of the perforations provided in the diaphragms 7 in the cell shown in FIG. 4, the solution flows through the anode side 6 and / or the cathode side 8 per unit time. The amount can be controlled efficiently. The permeability of the diaphragms 7 can be chosen separately for the diaphragms 7 on the anode side 6 and / or for the diaphragms 7 on the cathode side 8. Properly control the amount of solution per unit time flowing access to the diaphragm bags on the anode side 6 and / or the cathode side 8 via the diaphragms 7 with respect to the amount of solution per unit time to be supplied to the intermediate space 11. By this, the fluid static pressure of the separator solution 5 disposed in the intermediate space 11 can be adjusted to be higher than the fluid static pressure of the electrolyte solution contained in the diaphragm bags located in the separator solution 5. Therefore, it is possible to prevent undesirable flow of the electrolyte solution spaced from the diaphragm bag and passing through the diaphragm 7 toward the intermediate space 11. By appropriately determining the dimensions of the overflow channel 13, for example by placing the overflow channel at a suitable height, the intermediate space 11 and the anode side 6 and / or the cathode side 8 according to FIG. 4. The fluid static pressure difference between them does not rise too high and any excess separator solution can be ensured to flow out of the cell through the overflow channel 13. Each can also influence the formation of the hydrostatic pressure difference by determining the dimensions and position of the outlets 15. When the diameter of the perforations that can be provided in the diaphragms 7 is large, with the permeability of the diaphragms 7, the fluid static pressure difference essentially flows through the anode side 6 and the cathode side 8 per unit time. The amount of the solution to be limited is defined. Based on the description of the present invention, the above-described design of the dimensions of the electrolysis cell and the placement of the perforations is a routine test that is apparent to those skilled in the art.

As mentioned above, in some embodiments of the present invention, it is not necessary to directly supply the starting solution and / or the circulating solution to the anode side 6 and / or cathode side 8, for example the diaphragm bags of the electrolysis cell. In essence, all solutions in the device circulate through the intermediate space 11. The diaphragms 7 are completely impermeable to the solution, and the circulating solution and / or the starting solution are on the anode side 6 and / or the cathode side 8, for example with diaphragm bags, directly and in an intermediate space 11. It is selected so that it can be supplied without passing through. In some other embodiments of the invention, instead of the diaphragms 7, an ion selective membrane can be used, for example which only penetrates any type of ions.

In the electrolysis cell according to FIG. 4, the electrolysis structure is covered with a protective film 17, thereby for example with nitrogen gas or some other inert gas to prevent possible oxidation caused by air or the surrounding environment. The intermediate space 11 can be pressed. The diaphragm bags can also be closed and pressurized with nitrogen to prevent oxidation.

The cell structure of FIG. 4 enables reliable separation of the anolyte and catholyte in the electrolysis cell, which reduces premature oxidation and / or reduction reactions. As a result, by using the electrolysis cell structure according to FIG. 4, good efficiency is achieved in the present method. In addition, the risk of premature precipitation of the yield metal powder in the electrolysis cell is reduced, which improves the reliability of the method and makes the equipment easier to maintain.

Example

By applying the method according to the block diagram shown in FIG. 3, in a device basically showing the type shown in FIG. 2, a copper powder was prepared using an aqueous sulfuric acid solution as a starting solution, the solution containing V ^{3 +} cations. do. In this starting solution, the measured sulfuric acid concentration was about 500 g / l and the measured vanadium concentration was about 16 g / l. The feed material used was a class A cathode copper plate, which also serves as the anode of the electrolysis cell. The cathode used was a lead plate measuring 275 mm x 130 mm. In test conditions, the solution temperature was approximately 20-35 ° C.

The starting solution was fed into the electrolysis cell and the copper anode was oxidized and dissolved in the anolyte. The measured content of dissolved copper was approximately 4 g / l. Then, the anolyte solution was guided on the anode side, and the catholyte solution was guided on the cathode side to the precipitation chamber, in which the precipitation chamber was a glass bottle. The mixing ratio of the anolyte solution and the catholyte solution was 1: 3. As a result of the mixing operation, copper powder was formed in the precipitation chamber as described above. Electron microscope images of the obtained copper powder are shown in FIG. 5; From these images it can be seen, for example, that the size distribution of the copper particles is quite homogeneous, no large particle aggregates are produced and the average size of the particles is below the micrometer range.

Although some examples and embodiments illustrating the invention are described as a method of making a copper powder, based on this description of the invention, those skilled in the art will appreciate that when applying various embodiments of the invention other than copper Powders of other metals can also be readily produced. Likewise, based on the description of the present invention, those skilled in the art can readily use other mediating metals and / or acids than those listed in the above examples in various embodiments of the present invention. The present invention is not limited to only the above-described embodiments, and many various changes can be made within the scope of the appended claims.

Claims (26)

As a metal powder manufacturing method,
In the method for producing a metal powder, in which the dissolved yield metal is mixed with a solution containing at least one intermediate metal in order to precipitate the dissolved yield metal into the yield metal powder (14),
The method comprises:
The first portion of the acid-containing starting solution is moved as an anolyte 1 to the anode side 6 of the electrolysis cell, in contact with a feed material comprising the anode 2 and the yield metal; A second portion of the acid-containing starting solution, which also comprises an intermediate metal in addition to an acid, is moved to the cathode side 8 of the electrolysis cell as the catholyte 3 to come into contact with the cathode 4;
The yielding metal is oxidized and dissolved in the anolyte (1) by conducting current at the anode (2);
The intermediate metal contained in the second part of the starting solution is reduced at the cathode side (8); And
The anolyte solution and the catholyte solution are transferred to the precipitation chamber 12 to mix the second portion of the starting solution comprising the oxidized yield metal and the reduced intermediate metal dissolved in the first portion of the starting solution. Metal powder production method to be used. The method of claim 1,
Wherein the first portion of the starting solution comprises an intermediary metal for increasing dissolution of the yield metal at the anode side. The method according to claim 1 or 2,
The first part of the circulating solution formed as a result of the mixing of the anolyte solution and the catholyte solution is returned to the anolyte (1). The method of claim 3, wherein
Wherein the first portion of the starting solution consists of the first portion of the circulating solution. The method according to claim 3 or 4,
The second part of the circulating solution formed as a result of the mixing of the anolyte solution and the catholyte solution is returned to the catholyte (3). The method of claim 5, wherein
And the second portion of the starting solution consists of the second portion of the circulating solution. The method according to claim 5 or 6,
The circulating solution is essentially completely returned to the electrolyte solution, so that the circulating solution consists essentially of the first portion of the circulating solution and the second portion of the circulating solution. The method according to any one of claims 1 to 7,
The method for producing metal powder, characterized in that the anolyte (1) and the catholyte (3) are mechanically separated by an electrically conductive diaphragm (7). The method according to any one of claims 1 to 8,
An electrically conductive separator solution 5 is provided between two diaphragms 7 separating the anolyte 1 and the catholyte 3 to prevent premature mixing of the anolyte 1 and the catholyte 3. Metal powder manufacturing method, characterized in that guided from. 10. The method according to any one of claims 1 to 9,
The yield metal is a metal powder manufacturing method, characterized in that copper. 10. The method according to any one of claims 1 to 9,
The yield metal is a metal powder manufacturing method, characterized in that selected from the following group, nickel, cobalt, zinc, silver, gold, ruthenium, rhodium, palladium, osmium, iridium, platinum, manganese, zirconium, tin, cadmium and indium. 12. The method according to any one of claims 1 to 11,
The intermediate metal is vanadium, characterized in that the metal powder production method. 12. The method according to any one of claims 1 to 11,
The intermediate metal is a metal powder production method, characterized in that selected from the group of titanium, chromium and iron. 12. The method according to any one of claims 1 to 11,
The medium metal is a metal powder manufacturing method, characterized in that selected from the following group, manganese, zirconium, molybdenum, technetium, tungsten, mercury, germanium, arsenic, selenium, tin, antimony, tellurium and copper. 15. The method according to any one of claims 1 to 14,
The feed material comprising the yield metal is located at the anode (2). The method according to any one of claims 1 to 15,
And the yield metal is selected such that the selected yield metal is dissolved in the anolyte (1) as a soluble salt of the acid contained in the first portion of the starting solution. 17. The method according to any one of claims 1 to 16,
Wherein the starting solution comprises sulfuric acid. 18. The method according to any one of claims 1 to 17,
The content of sulfuric acid in the starting solution is at least 50 g / l, and preferably 50 g / l to 1,500 g / l metal powder production method. The method according to any one of claims 1 to 18,
The starting solution comprises a hydrochloric acid or nitric acid. In the apparatus for producing a metal powder by mixing the dissolved yield metal and a solution containing at least one intermediate metal to precipitate the yield metal powder (14),
The apparatus comprises:
An electrolysis cell for dissolving the yield metal located on the anode side of the electrolysis cell and oxidizing it in the anolyte and reducing the dissolved intermediate metal located on the cathode side 8 of the electrolysis cell on the cathode side;
A precipitation chamber 12 essentially separated from the electrolysis cell; And
From the outside of the electrolysis cell, the anode side 6 of the electrolysis cell and the cathode side 8 of the electrolysis cell for mixing the catholyte solution containing the reduced intermediate metal and the yield metal dissolved in the anolyte solution And means for supplying an anolyte solution and a catholyte solution from to the precipitation chambers (12), respectively. 21. The method of claim 20,
The electrolysis cell comprises an electrically conductive diaphragm 7 between the anode side 6 and the cathode side 8 of the electrolysis cell for mechanically separating the anode side 6 and the cathode side 8. An apparatus for producing a metal powder. 22. The method according to claim 20 or 21,
The electrolysis cell comprises two electrically conductive diaphragms 7 between the anode side 6 and the cathode side 8 of the electrolysis cell and is provided in the space left between the two diaphragms 7. An apparatus for producing a metal powder, characterized in that the anode side (6) and the cathode side (8) are mechanically separated by the separator solution (5). The method according to any one of claims 20 to 22,
The yielding metal supplied to the anode side (6) of the electrolysis cell is located at the anode (2) of the electrolysis cell. The method according to any one of claims 20 to 23,
The electrolysis cell comprises at least one bag defined by a diaphragm (7) to hold an anolyte and / or catholyte inside the bag. The method according to any one of claims 20 to 24,
The electrolytic cell comprises means for guiding the separator solution 5 from the space left between the two diaphragms 7 to the anode side 6 and / or the cathode side 8. Device for manufacturing. The method according to any one of claims 20 to 25,
Electrolyte is an apparatus for producing a metal powder, characterized in that disposed in an oxygen-free environment to prevent oxidation of the yield metal and / or the intermediate metal contained in the electrolyte.

Images