Apparatus and method for performing electrolysis, and electrode unit for such apparatus

Abstract

The apparatus for performing the electrolysis process comprises a container (2;53) having an interior container (3;54) for containing at least one electrolyte; an array (26;77) of spaced-apart first electrodes (5a, b, 6a-d; 38a, b, 42; 56a, b, 57a-f; 78a, b) arranged inside the container (2;53); and at least one second electrode (7a, b; 58a, b; 79), wherein at least a portion of the surface of the at least one second electrode (7a, b; 58a, b; 79) is exposed to at least a portion of the interior container (3;54) for containing at least one of the at least one electrolytes. The system includes a current supply system for causing current to flow through at least one electrolyte between the main surface of the first electrode (5a, b, 6a~d; 38a, b, 42; 56a, b, 57a~f; 78a, b) and the main surface of the first electrode (7a, b; 58a, b; 79) by establishing a potential difference between the main surface of the first electrode (5a, b, 6a~d; 38a, b, 42; 56a, b, 57a~f; 78a, b) on the one hand and the second electrode (7a, b; 58a, b; 79) on the other hand, such that the first electrode (5a, b, 6a~d; 38a, b, 42; 56a, b, 57a~f; 78a, b) has polarity opposite to that of the second electrode (7a, b; 58a, b; 79). The array (26;77) of first electrodes (5a, b, 6a~d; 38a, b, 42; 56a, b, 57a~f; 78a, b) includes at least one end electrode (5a, b; 56a, b; 78a, b) spaced between one of the second electrodes (7a, b; 58a, b; 79) on the one hand and all of the other first electrodes (6a~d; 38a, b, 42; 57a~f) of the array (26;77) on the other hand. In addition to the end electrodes (5a, b; 56a, b; 78a, b), the array (26;77) of first electrodes includes at least one first electrode (6a~d; 38a, b, 42; 57a~f) other than the end electrodes (5a, b; 56a, b; 78a, b).The device is configured to establish a potential at least on the main surface of the end electrodes (5a, b; 56a, b; 78a, b) that is different from the potential at the main surface of the first electrodes (6a~d; 38a, b, 42; 57a~f) in the array (26; 77) other than the end electrodes (5a, b; 56a, b; 78a, b), by making the potential of each of the second electrodes (7a, b; 58a, b; 79) closer to the potential of each of the second electrodes.

Description

[Technical Field]

[0001] The present invention is an apparatus for performing an electrolytic process, and this apparatus is A container having an interior for containing at least one type of electrolyte; An array of first electrodes, spaced apart and placed inside a container; The at least one second electrode is positioned such that at least a portion of its surface is exposed to at least a portion of the interior of a container for containing at least one of at least one electrolytes; A current supply system for causing current to flow through the second electrode and the main surface of the first electrode through at least one electrolyte by establishing a potential difference between the main surface of the first electrode on the one hand and the second electrode on the other, such that the first electrode has a polarity opposite to that of the second electrode. Includes, The array of first electrodes includes at least one end electrode spaced between one of the second electrodes on the one side and all of the other first electrodes of the array on the other side. The present invention relates to an apparatus in which, in addition to end electrodes, the array of first electrodes includes at least one first electrode other than the end electrodes.

[0002] Furthermore, the present invention relates to a method for performing an electrolytic process using an apparatus, wherein the apparatus is A container having an interior for containing at least one type of electrolyte; An array of first electrodes, spaced apart and placed inside a container; At least one second electrode, wherein at least a portion of its surface is positioned to be exposed to at least a portion of the interior of a container for housing at least one of at least one electrolytes. Includes, The array of first electrodes includes at least one end electrode spaced between one of the second electrodes on the one side and all of the other first electrodes of the array on the other side. In addition to the end electrodes, the array of first electrodes includes at least one first electrode other than the end electrodes. This delicious, The steps include providing at least one type of electrolyte in a container; The steps include: establishing a potential difference between the main surface of the first electrode and the second electrode on the other side, such that the first electrode has a polarity opposite to that of the second electrode, thereby causing a current to flow through at least one electrolyte through the main surface of the second electrode and the first electrode; This includes methods.

[0003] Furthermore, the present invention relates to an electrode unit for use in an electrolytic process, wherein the electrode unit is An array of electrodes in the form of sheets, each containing a mesh of a conductive material, having at least one electrical contact point, where the main surfaces of neighboring electrodes are arranged facing each other; At least one current feeder for electrically connecting at least one of the electrode arrays to a current source located outside the electrode unit; Multiple electrical conductors, each connecting one of the electrical contact points to one of the current feeders. This relates to electrode units, including those mentioned above.

[0004] Furthermore, the present invention relates to an apparatus for performing an electrolytic process including such an electrode unit. [Background technology]

[0005] Patent Document 1 discloses an electrode array comprising a plurality of individual electrode segments. The electrode segments are independently wired and physically isolated from one another. Means are provided for individually electrically biasing each electrode segment and for individually controlling the amount of current to each electrode segment. This provides obtaining a selected area and configuration of the electrode current profile, thereby accommodating differently sized and differently shaped articles to be plated or etched. In the disclosed embodiments, the anode segments are supported on an insulating rack. The anode array is presented in a planar format.

[0006] Patent Document 2 discloses a device and method that enables a large surface substrate having a relatively high resistance to be provided with a thin layer of nearly homogeneous thickness by electrochemical deposition. The counter electrode is divided into a plurality of electrode segments. Different voltage differences can be applied between each individual electrode segment and the substrate to be coated. In the disclosed embodiment, the electrode strip is fixed to a plastic plate. A metal rail guided upward on the back of the plastic plate serves to provide electrical contact and is connected to each electrode strip by a metal screw. When a homogeneous current density is achieved across the substrate, the voltage generally increases from the top segment electrode to the bottom segment electrode. In one embodiment, each counter electrode segment is controlled by its own voltage source, one pole of which is connected to each counter electrode segment and the other pole is connected to the substrate to be counted. In an alternative embodiment, all counter electrode segments are controlled by a single voltage source, and an appropriate electrical resistance (adapted with respect to its electrical parameters) is connected between this voltage source and each individual counter electrode segment.

[0007] Patent Document 3 discloses a method for oxidizing manganese species in a processing device. The device comprises at least one anode unit and at least one cathode. In one embodiment, the anode unit is a defined compartment containing at least one anode in the center of at least one anode unit. The anode is provided as a vertically oriented layer stack containing a plurality of 8 to 20 anode layers (they are expanded metals having individual surface coefficients slightly greater than 2). The at least one anode unit is confined by a housing containing at least one permeable barrier (it is a Nafion-type film). The distance between the plurality of anode layers is fixed by spacers. The cathode is provided on the opposite side of the at least one anode unit. Current is supplied to the at least one anode and at least one cathode. The anode current density is approximately 1 A / dm 2 On the other hand, the cathode current density is approximately 10 A / dm 2 The processing device is filled with a cathode solution consisting of aqueous phosphoric acid (70 wt%), and the liquid is continuously pumped through the anode unit. As the liquid flows through the anode unit, it comes into contact with the anode layer of the stack, and manganese species with an oxidation state below +7 are continuously reoxidized to permanganate ions (i.e., manganese species with an oxidation state of +7).

[0008] In this type of device, a shielding effect exists in the anode layer stack. This has two consequences. First, there is a higher current density on each side of the layer oriented toward the nearest cathode than on the opposite side (naturally, the only exception being the anode layer precisely in the center of a symmetrical stack). Second, the current density on the outward-oriented surface of the anode layer at the end of the stack near the cathode is significantly greater than that on any anode surface inside the stack. In principle, the number of reactions per unit current increases with current density at low values. In known devices, the only way to increase the efficiency of the inner anode layer in a vertically oriented layer stack is to increase the total current supply across all anode layers, but this results in even higher current densities on the outer surfaces and does not result in a proportional increase in yield.

[0009] A different problem that may arise with anode layers having a surface coefficient of 2 is that the purpose of providing them with a large effective surface area for a given volume means that they may be relatively thin and flexible. In particular, when electrolytes are pumped through them, the surfaces of neighboring anode layers may come into contact with each other, and therefore spacers are required. Spacers at only selected points may be insufficient in number or size, as this may cause the anode layers to bulge. The more spacers there are, or the larger the surface area that the spacers cover, the more the anode layer surface area is reduced, thereby decreasing the available effective surface area. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] U.S. Patent No. 5,156,730 [Patent Document 2] WO02 / 053806A2 [Patent Document 3] WO2022 / 263483A1

Summary of the Invention

Problems to be Solved by the Invention

[0011] A first object of the present invention is to provide an apparatus and method of the type defined in the opening paragraph that are more efficient in terms of the number of reactions per unit current.

[0012] A second independent object of the present invention is to provide an electrode unit that enables the use of relatively thin electrodes that are positioned in close proximity and have a relatively high effective surface area, and an apparatus including such an electrode unit.

Means for Solving the Problems

[0013] The first object is achieved according to a first aspect by an apparatus according to the present invention, which is characterized in that it is configured to establish a potential different from the potential at the main surface of the first electrode in the array other than the end electrodes at least at the main surface of the end electrodes by bringing the potential of each of the second electrodes closer to it.

[0014] This apparatus is based on the discovery that the number of reactions does not increase proportionally to the current density (current per unit area of ​​geometric surface area) on the surface of any given first electrode, but rather plateaus. This means that the increased proportion of current flowing through the electrolyte via that first electrode does not contribute to the desired electrolytic process. Instead, that proportion results in the production of by-products (e.g., hydrogen and / or oxygen in the case of aqueous electrolytes). If, as in the prior art, all first electrodes in an array are connected to the same rectifier circuit, there will be a relatively large current flowing through the end electrodes. In fact, it has been found that about half of the total current passes through the end electrodes in such a setup. Thus, the current density through the main surface of the end electrodes will be high. The current density on the main surface of the other first electrodes will be relatively low. Adding more first electrodes to the array will increase the yield, but only slightly. This is because the current density on the surface of each additional first electrode that is not an end electrode will be extremely low. It has been found that increasing the total current worsens the uneven current distribution and degrades the overall efficiency. In contrast, the apparatus according to the present invention is configured to establish a potential at least on the main surface of the end electrodes that is different from the potential on the main surface of the first electrodes in the array other than the end electrodes, by making it closer to the potential of the second electrode, so that the current distribution across the first electrodes is altered compared to a situation where the respective potentials at the interconnection between the current supply system and the main surface of each first electrode are all the same value. This alteration reduces the current flowing through the end electrodes, for example, as a proportion of the total current flowing through all the first electrodes in the array. Thus, by allowing the current flowing through each first electrode to be more uniform, more of the first electrodes can be operated at current levels close to but below the level at which efficiency begins to plateau.The current distribution across the first electrodes in the array approaches the optimal state, where a few electrodes (mainly end electrodes) have high current density and low yield, as well as many first electrodes have very low current density and therefore high relative yield but low absolute yield.

[0015] This apparatus is for performing an electrolytic process, which may, but is not limited to, the electrolytic oxidation of ions such as manganese species. Alternative examples include, for example, electrochemical hydrolysis for obtaining hydrogen, electroplating, electrorefining, and plating out ionic species (e.g., copper) from a solution. The apparatus includes a container for containing at least one electrolyte. The container does not need to be closed in all embodiments. The container can be arranged to contain two or more electrolytes (in particular, cathodes and anodes) having different compositions, which are separated to prevent the respective compositions from becoming homogenized. The apparatus can be configured so that at least one of the at least one electrolyte flows through the container during use, for example, by providing at least one inlet and at least one outlet that allows at least one of the at least one electrolyte to flow through the container.

[0016] This device includes an array of first electrodes, spaced apart and arranged within a container. The spacing allows for the inclusion of electrolytes in the space between the opposing sides of neighboring first electrodes. The space does not need to be empty; it is sufficient if the spacing ensures that neighboring first electrodes are electrically isolated from one another (except for any electrolytes in the space between them). The result is a device that is relatively compact but provides a large total effective surface area for the first electrodes.

[0017] The first electrode is generally an electrode having opposing primary surfaces. In an array of first electrodes, each end electrode spaced between a second electrode and all other first electrodes has one primary surface facing the second electrode and one primary surface facing the primary surface of a neighboring first electrode. The opposing primary surfaces of the first electrodes in the array spaced between other first electrodes each face the primary surface of their respective neighboring first electrodes.

[0018] The electrodes can generally be in the form of a sheet (for example, a liquid-permeable sheet) with a thickness several times smaller than its spread in the other two dimensions. The thickness is the distance between the two sides of the first electrode just mentioned, i.e., the distance between the sides of the first electrode such that at least one faces one of the two sides of a neighboring first electrode in the array. The primary surface is the surface at these two sides. The thickness of each first electrode can be on the order of micrometers, for example, in the range of 1 to 2 μm. The spacing between first electrodes in the array can be on the order of 0.5 to 5 mm, for example, in the order of 1 to 3 mm. The first electrodes can also each contain an array or grid of electrically interconnected bars, which are arranged to define the overall sheet shape, for example, by lying on a common plane.

[0019] The first electrodes may be plate-shaped, but do not necessarily have to be freestanding, nor do they necessarily have to be impermeable to liquids, or more preferably, they are impermeable to liquids. When plate-shaped, they are therefore arranged in a stack, but do not necessarily have to be oriented horizontally, or more preferably, they are oriented horizontally. Alternatively, the first electrodes can be configured in a cylindrical shape (e.g., a circular cylinder) and can be arranged surrounding each other (e.g., concentrically). The first electrodes can be rigid or relatively flexible, in which case they are mounted, for example, to avoid contact between opposing sides of neighboring first electrodes. One or more spacers between opposing sides of neighboring first electrodes can be provided for this purpose.

[0020] This device includes at least one second electrode. For example, one second electrode may be present on each side of the array of first electrodes, and each of these second electrodes has one main surface facing at least two proximal main surfaces of each of the end electrodes. Alternatively, a single such second electrode may be present. The shape of the second electrode may be adapted to at least the proximal end electrodes. That is, if the first electrodes are planar, the second electrodes are also planar. If the first electrodes are curved, the second electrodes are curved with the same sign of curvature as the first electrodes (e.g., with the same radius of curvature). However, it should be noted that not all first electrodes in the array need to have the same shape (when viewed in a plan view facing the main surface), size, or mesh or aperture size.

[0021] In one embodiment, the array of first electrodes is an array of first electrodes arranged vertically. That is, the direction of progression from one first electrode to the next is mainly horizontal. The first electrodes are arranged in an upright orientation. The normals to the main surfaces of the first electrodes are mainly oriented horizontally.

[0022] The apparatus includes a current supply system for causing current to flow through at least one electrolyte through the main surfaces of the second and first electrodes by establishing a potential difference between an interconnection to the main surface of the first electrode on the one hand and an interconnection to each of the second electrodes on the other hand, such that the first electrode has polarity opposite to that of the second electrode. Thus, the terms first electrode and second electrode are used here to distinguish between electrodes that have opposite polarity when in use. The first electrode may, among other things, be an anode, and the second electrode may be a cathode. The interconnection to the main surface of the first electrode is one or more parts that electrically interconnect the current supply system to the main surface of the first electrode. One or more parts of the interconnection to the first electrode may include parts integral with the first electrode, as will be further described below with reference to specific embodiments. A current supply system generally includes at least one current source connected to at least one of the first electrodes, the value of the current supplied or drawn by each current source being set separately from the current values ​​of the other current sources, but each current source setting only the total current flowing through all the first electrodes connected to it. Those first electrodes are located in parallel circuit branches connected in series with the current source. If the device is configured to be powered by an AC current supply unit or a three-phase current supply unit at the installation site, each current source may include its own current rectifier.

[0023] The array of first electrodes includes at least one end electrode spaced between one of the second electrodes on the one hand and all the other first electrodes of the array on the other hand. If the array is placed between two second electrodes, there will be two end electrodes. If only one second electrode is present, the first electrode adjacent to that second electrode will be the end electrode.

[0024] The device is configured to establish a potential at least on the main surfaces of the end electrodes that is different from the potential on the main surfaces of the first electrodes in the array other than the end electrodes, by making the potential of each of the second electrodes closer to the potential of the end electrodes. However, the potential can vary across each main surface with respect to the distance from the interconnection between the power supply system and its main surface. The potential difference between the main surfaces mentioned is at least between corresponding locations on the corresponding main surfaces, where the corresponding surfaces are corresponding in the sense that they face the same direction, and the locations are corresponding in the sense that they are aligned in the direction in which the first electrodes are positioned in the array. However, generally, the potential difference between the first electrodes will be greater than the potential across the main surfaces of any particular first electrode. The main surfaces opposite any particular first electrode can, but do not have to be, at the same potential at their corresponding locations. Some or all of the main surfaces of the first electrodes other than the end electrodes may be at the same potential, or they may be at different potentials.

[0025] In one embodiment, in addition to end electrodes, the array of first electrodes includes at least two other first electrodes, and the device is configured to establish different potentials for each of these at least two other first electrodes on their main surfaces, such that the difference in potential of the most proximal of at least two second electrodes increases according to how much of the first electrode is spaced between the first electrode and the most proximal second electrode.

[0026] Therefore, it is possible to further equalize the currents flowing through each individual first electrode. In particular, the current values ​​can all be brought down to a level where efficiency begins to decrease, or just below that level. If there are two second electrodes and the array of first electrodes is placed between the opposing surfaces of the second electrodes, then there will be two end electrodes in the array. The device will then be configured to establish a potential that increases from the end electrodes to one or two electrodes in the middle of the array and then decreases again on the main surface of the other first electrode. This is because the most proximal second electrode will be different for the first electrodes in one half of the array and for the first electrodes in the other half of the array. The current distribution will be such that the current density on the main surface of the first electrode is approximately equal to, and especially close to, the optimal current density value. If there is only one second electrode, then there will be only one end electrode. The device is then configured to establish a potential that increases on the main surface of the other first electrodes, from the end electrode to the first electrode at the opposite end of the array (which has the most first electrodes spaced between itself and the (sole) end electrode). It should be noted that a potential difference will exist between any two main surfaces of any one of the first electrodes. However, these will be smaller than if all the first electrodes were connected in parallel to each other and collectively in series to a single current source. In general, such differences will be negligible.

[0027] In one embodiment of the apparatus, the current supply system includes at least two current sources, which are electrically connected in series to each of the disjoint subsets of the first electrodes in the array, respectively, via their respective current feeders.

[0028] In other words, each current source is connected in series only to its respective subset of the association of the first electrode, and these subsets are independent of each other. In set theory in mathematics and formal logic, two sets are said to be independent of each other if they have no common elements.

[0029] The current source can be a controllable current source, allowing the current supplied to each subset of the first electrodes to be controlled to achieve a set value. In either case, the current source allows for separate current supply, and the value of the total current supplied to each subset is different with respect to at least two current sources (e.g., all current sources) and is set individually with respect to each current source. One or more of the subsets can be formed by only a single first electrode. Using only multiple current sources, it is possible to implement the overall concept of establishing a potential at least on the main surface of the end electrodes that is different from the potential on the main surface of the first electrodes in the array other than the end electrodes. If this is done with respect to each first electrode in the array, in the case of a symmetrical arrangement with two second electrodes on either side of the array of first electrodes, each subset can contain two first electrodes arranged symmetrically with respect to the middle of the array. Otherwise, generally, there will be one first electrode in each subset. Furthermore, a larger subset is possible, particularly when the overall concept behind the device is realized using pre-resistors. Each current source may include at least one voltage rectifier specific to that current source (i.e., not shared with other current sources). Alternatively, current sources may share voltage rectifiers but have their own DC / DC converters, allowing for independent current supply to a subset of first electrodes connected to that current source. Naturally, voltage rectifiers will not be present for devices to be used in a plant with a DC current microgrid. In this context, a current feeder is an electrically interconnected part or group of parts (i.e., one or more electrical conductors). Two or more current feeders may exist for one or a combination of current sources and subsets of first electrodes. Current feeders will not be shared among such combinations.The current feeder extends through the inside of the container. The current feeder is electrically connected to the current source via a conductor (for example, a wire extending outside the container).

[0030] In embodiments of the apparatus, at least two of the first electrodes are electrically connected in series with a common current source included in the current supply system, and pre-resistors are electrically positioned between the main surfaces of the first electrodes electrically connected to the common current source, and the total resistance of the pre-resistors between the common current source and the first electrodes connected to the common current source differs among the first electrodes connected to the common current source and decreases depending on how much of the first electrodes are spaced in the array between the first electrodes and the nearest of at least one second electrode.

[0031] This is another way of realizing the concept of establishing a potential that is different at least at the main surface of the end electrodes from the potential at the main surface of the first electrodes in the array other than the end electrodes, by making the potential of each of the second electrodes closer to the potential of the end electrodes. In particular, this embodiment allows the potential to be different for each first electrode throughout the array without using a current supply system with a large number of separate current sources. The potential difference to the nearest second electrode is highest at the first electrode furthest from that second electrode. A common current source can be configured or controlled only to supply a specific sum of current to all first electrodes connected to that common current source or to draw a specific sum of current from the first electrodes. Equalization between individual first electrodes is achieved by pre-resistors. As stated, this embodiment can be combined with embodiments using multiple separate current sources.

[0032] In a particular example of this embodiment, the first electrodes, electrically connected in series with a common current source, are connected in parallel with respect to each other, and pre-resistors are placed in each branch of the parallel circuit in which the first electrodes are contained, such that the total resistance of the pre-resistors differs between the branches, and decreases depending on how much of the first electrodes are spaced in the array between the first electrode in the branch and the nearest of at least one second electrode.

[0033] This example is relatively easy to design and implement by using an appropriate resistance value for the pre-resistor.

[0034] In a particular example of the embodiment of the apparatus, the first electrodes are provided in the form of a sheet comprising at least two of the first electrodes, electrically connected in series with a common current source included in the current supply system, with pre-resistors electrically positioned between the main surfaces of the first electrodes electrically connected to the common current source, the total resistance of the pre-resistors between the common current source and the first electrodes differs between the first electrodes connected to the common current source and decreases depending on how much of the first electrodes are spaced in the array between the first electrodes and the nearest of at least one second electrode, the first electrodes are provided in the form of a sheet comprising at least one main section defining a main surface, the sheet forming at least one of the first electrodes further comprising at least one section, the at least one section forming one of the pre-resistors, the main section interconnecting with at least one contact point, the at least one contact point electrically connecting the first electrode to the rest of the circuit in which the first electrode comprises.

[0035] Therefore, the pre-resistor is effectively integrated into the first electrode. This results in a compact arrangement that is relatively easy to manufacture. The section forming one of the pre-resistors can be cut into the sheet, for example, in the form of a path from the contact point to the main section, and this path lies in the same plane when the sheet is arranged in a planar form. In this context, the term sheet is used simply to indicate that the lateral dimension of two opposing main surfaces is much greater than the thickness corresponding to the dimension between the two opposing main surfaces. The sheet can be permeable to liquids, does not need to have a rectangular shape, or can be flexible enough to be rolled up, for example.

[0036] An example of any embodiment of the apparatus is that at least two of the first electrodes are electrically connected in series with a common current source included in the current supply system, and pre-resistors are electrically positioned between the main surfaces of the first electrodes electrically connected to the common current source, and the total resistance of the pre-resistors between the common current source and the first electrodes differs between the first electrodes connected to the common current source, and decreases depending on how much of the first electrodes are spaced in the array between the first electrodes and the nearest of at least one second electrode, at least one The present invention further includes a pre-resistor configuration, which provides at least one first electrical contact point electrically connected to a current source included in a current supply system, and a plurality of second electrical contact points, at least two of the second electrical contact points electrically connected to different first electrodes, and current paths of different electrical resistances are formed in the pre-resistor configuration between at least one of the at least one first electrical contact point and the second electrical contact points electrically connected to different first electrodes.

[0037] This example can be implemented without substantial modification to the existing first electrode design, other than providing a connection to a second electrical contact point. The pre-resistor formwork is generally a molded continuous mass of one or more electrically conductive materials. Suitable materials include, for example, titanium. This formwork does not need to be self-supporting and, in principle, can have any shape. This formwork can be formed, for example, by molding, cutting (e.g., laser cutting), milling, welding, soldering, or any combination thereof. Sections of the current path can be shared between current paths.

[0038] Alternatively, it would be possible to use readily available resistors positioned so as not to come into contact with the electrolyte and connected to each of the first electrodes, although this would involve additional interconnections.

[0039] In a particular example of any version of the embodiment of the apparatus, the apparatus further includes at least one pre-resistor configuration, the pre-resistor configuration is electrically connected in series with a common current source included in the current supply system, and pre-resistors are electrically positioned between the main surfaces of the first electrodes electrically connected to the common current source, and the total resistance of the pre-resistors between the common current source and the first electrodes differs between the first electrodes connected to the common current source, and decreases depending on how much of the first electrodes is spaced in the array between the first electrodes and the nearest of at least one second electrode. The device is provided with at least one first electrical contact point and a plurality of second electrical contact points, at least two of the second electrical contact points being electrically connected to different first electrodes, and current paths of different electrical resistances are formed in the pre-resistor form between at least one of the at least one first electrical contact point and the second electrical contact points being electrically connected to different first electrodes, and each of the at least one of the first electrodes is electrically connected to at least two of the second electrical contact points through electrical conductors connected to electrical contact points that are spaced apart from the first electrodes.

[0040] This embodiment reduces the voltage difference across the main surface of the first electrode. Therefore, a more uniform distribution of current density exists between the electrolyte and their surfaces. Furthermore, the more electrical conductors used, the lower the amount of ohmic heating of each individual conductor. Additionally, separating them allows for more effective cooling by heat conduction (e.g., through the electrolyte).

[0041] In a particular example of any version of the embodiment, the apparatus further includes at least one pre-resistor configuration, the pre-resistor configuration is electrically connected in series with a common current source included in the current supply system, and pre-resistors are electrically positioned between the main surfaces of the first electrodes electrically connected to the common current source, and the total resistance of the pre-resistors between the common current source and the first electrodes differs between the first electrodes connected to the common current source, and decreases depending on how much of the first electrodes are spaced in the array between the first electrodes and the nearest of at least one second electrode. The present invention provides at least one first electrical contact point connected to and a plurality of second electrical contact points, at least two of the second electrical contact points being electrically connected to each different first electrode, and current paths of different electrical resistances are formed in the pre-resistor configuration between at least one of the at least one first electrical contact point and the second electrical contact points being electrically connected to each different first electrode, the pre-resistor configuration comprising a sheet in which the current paths, which are separated from each other, are formed, and the current paths of different electrical resistances differ in terms of at least one of length and cross-sectional area perpendicular to the direction of current path propagation along the length of the current path.

[0042] The term "sheet," again, is used simply to indicate that the lateral dimension of the opposing main surfaces of the formed material is much greater than the thickness corresponding to the dimension between the two opposing main surfaces. The sheet does not need to have a rectangular outline, or it can be flexible enough to be rolled up, for example. In particular, the formed material can be, for example, a foil, a plate, or a layer supported on a substrate. The cross-sectional area can be made to differ only due to differences in the width of the current path, and the height corresponds to the thickness of the sheet. In that case, the sheet can have a uniform thickness. The current path can be obtained by cutting (e.g., laser cutting) the outline of the current path from a sheet (e.g., a rectangular sheet) that initially has a boundary that is a convex curve in a geometric sense. Thus, this embodiment can be obtained relatively easily. The material composition of the formed material can be, for example, uniform. The length of the current path can correspond to the length of its neutral axis. Variations in the length of the current path can be the main way in which different electrical resistances are set. Changes in width and / or height can be left for fine-tuning.

[0043] In a particular example of any version of the embodiment, the apparatus further includes at least one pre-resistor configuration, the pre-resistor configuration is electrically connected in series with at least one first electrode that is electrically connected to a common current source included in the current supply system, and pre-resistors are electrically positioned between the main surfaces of the first electrodes that are electrically connected to the common current source, and the total resistance of the pre-resistors between the common current source and the first electrodes differs between the first electrodes that are connected to the common current source, and decreases depending on how much of the first electrodes is spaced in the array between the first electrodes and the nearest of at least one second electrode. Provided are an electrical contact point and a plurality of second electrical contact points, at least two of the second electrical contact points being electrically connected to each different first electrode, and current paths of different electrical resistances are formed in a pre-resistor configuration between at least one of the at least one first electrical contact point and the second electrical contact points electrically connected to each different first electrode, the pre-resistor configuration includes a sheet in which the current paths are formed, which are separated from each other, and the current paths of different electrical resistances differ in terms of at least one of length and cross-sectional area perpendicular to the direction of current path propagation along the length of the current path, and the pre-resistor configuration is interposed between two of the first electrodes in an array.

[0044] This results in a particularly compact assembly with short electrical connections between the second electrical contact point and each of the first electrodes.

[0045] In a particular version of this embodiment, at least one of the second electrical contact points is electrically connected to the first electrode via an electrical conductor (for example, an electrical conductor placed in a bushing through which the conductor passes the other first electrode through which the conductor passes), the bushing being made of a material having a lower electrical conductivity than the electrical conductor.

[0046] Therefore, the bushings are electrically insulating, allowing the surface potential of the first electrode to be maintained at different values. The bushings are made from a material selected to withstand the electrolyte, which is not necessarily required in standard wiring. A standard first electrode design can be used, as it is only necessary for the conductor and bushing to provide it with an aperture through which it can pass.

[0047] In any embodiment, the apparatus further includes at least one pre-resistor configuration, the pre-resistor configuration is part of the current supply system, at least two of the first electrodes are electrically connected in series with a common current source included in the current supply system, and pre-resistors are electrically positioned between the main surfaces of the first electrodes electrically connected to the common current source, and the total resistance of the pre-resistors between the common current source and the first electrodes differs between the first electrodes connected to the common current source, and decreases depending on how much of the first electrodes are spaced in the array between the first electrodes and the most proximal of at least one second electrode. The pre-resistor is provided with at least one first electrical contact point electrically connected to a current supply source contained within, and a plurality of second electrical contact points, at least two of the second electrical contact points electrically connected to different first electrodes, and current paths of different electrical resistances are formed in the pre-resistor formation between at least one of the at least one first electrical contact point and the second electrical contact points electrically connected to different first electrodes, and the pre-resistor formation is at least partially covered by a housing made of a material having a lower electrical conductivity than the material of the pre-resistor formation.

[0048] The housing is electrically insulating, and there is no or limited leakage current from the pre-resistor formation (e.g., to the second electrode). Therefore, the pre-resistor formation can be partially or completely immersed in the electrolyte during use. The housing may or may not be able to touch the pre-resistor formation. A gap may exist between them.

[0049] In one embodiment of the apparatus, the first electrode is provided in the form of a liquid-permeable sheet.

[0050] Therefore, the first electrode can have a relatively high effective surface area relative to its volume. The sheet can have a surface coefficient of, for example, 1 or more, such as 1.4 or more, 1.7 or more, or even 2 or more or 2.2 or more, where the surface coefficient is a parameter corresponding to the total effective surface area per geometric area. The sheet can be, for example, a foam or a mesh (including a grid), or a laminate of such a sheet. A further effect of this embodiment is that the current path through the electrolyte between the first electrode and the second electrode, excluding the end electrodes, can be made shorter.

[0051] In this embodiment, at least two neighboring first electrodes are separated from each other by at least one spacer.

[0052] Therefore, the first electrodes do not need to be very rigid. Thus, their effective surface area can be relatively high relative to their volume. The spacers, on the one hand, ensure that the surfaces remain accessible. On the other hand, if the spacers are made from a material having a lower electrical conductivity than the material from which the first electrodes (especially the sheets) are fabricated, the spacers allow the surfaces of neighboring first electrodes to be maintained at different potentials. Thus, one or more spacers can be electrically insulating.

[0053] In any embodiment where the first electrode is provided in the form of a liquid-permeable sheet, the sheet includes a mesh.

[0054] This embodiment presents a simple method for providing a first electrode having a relatively high surface coefficient. The mesh can be, for example, woven, braided, welded, sintered, etched, or electroformed. Thus, the strands of material constituting the mesh can be separate or intertwined, but are not required. In certain embodiments, the mesh is made from expanded metal. The apertures in such a mesh can have, for example, a rhomboid or rhomboid shape. The strands of the mesh can be coated.

[0055] The first electrode is provided in the form of a liquid-permeable sheet, and at least two neighboring first electrodes are separated from each other by at least one spacer, the sheet including a mesh, in an example of any embodiment, the spacer includes threads of a material having a lower electrical conductivity than the material from which the mesh is made, the threads passing through at least one of the meshes included in the neighboring first electrodes in the form of a sequence of stitches.

[0056] This example allows for avoidance of contact between neighboring first electrodes, even when the mesh is relatively flexible. At the same time, the area covered by one or more spacers is relatively small. Assembly is relatively easy because there is no need to attach numerous separate spacer elements using individual fasteners. The threads can have diameters on the order of millimeters, for example, in the range of 0.5 to 5 mm, more specifically in the range of 0.5 to 2 mm. The threads are effectively electrically insulating because they have a lower electrical conductivity than the material from which the mesh is fabricated.

[0057] In embodiments of the apparatus, the first electrode includes at least one of lead, tantalum, platinum group metals, or alloys or oxides thereof (for example, at least one of platinum, platinum alloys, or platinum oxides) at least on its surface (for example, in the surface coating only).

[0058] Platinum group metals further include iridium group metals such as osmium, ruthenium, and iridium, which, like lead, are suitable with platinum or as alternatives to platinum. These are all relatively expensive, and their function is generally to enable the catalyst in the electrolyte around the first electrode to function optimally. Therefore, it may be useful to provide them only in surface coatings. When provided as surface coatings, such coatings can have thicknesses ranging, for example, between 0.5 μm and 50 μm, between 0.5 μm and 40 μm, or even between 0.5 and 2 μm. In particular, platinum forms a thin platinum oxide layer when the first electrode is used as an anode. In particular, it has been found that at high current density values, platinum loss can occur, leading to platinum-deficient islands and a decrease in overall performance. This effect is self-amplifying to a certain extent because the current density increases when islands are formed. However, a threshold current density exists, and below this threshold current density, platinum losses do not reduce the useful life of the electrodes to an unacceptable degree. The configuration of the apparatus (in particular, means that allow the current passing through the first electrodes to be more uniform) allows all or almost all of the first electrodes to operate below the threshold without wasting the first electrodes located far from the end electrodes.

[0059] Oxides (e.g., iridium oxide and / or tantalum oxide) can be used in applications where organic matter in wastewater is oxidized.

[0060] When the first electrode functions as a cathode, for example in a process for removing copper from an electrolyte, the first electrode may contain at least copper, at least on its surface (for example, only in a surface coating).

[0061] In embodiments of the apparatus, the first electrode is primarily made from an inert material (for example, a material containing at least one of titanium, niobium, and carbon).

[0062] The material can be selected based on its ability to withstand electrolytes over long periods of use, its compatibility with the chosen coating, its price, and its suitability for manufacturing as a mesh (e.g., expanded metal). A specific example is a niobium electrode coated with platinum.

[0063] In an embodiment of the apparatus, the array of first electrodes is at least partially enclosed by a housing, the second electrodes are located outside the housing, and the housing includes at least one selectively permeable membrane that separates the inside of the housing from the outside of the housing.

[0064] The housing can, for example, enclose the array of first electrodes up to the level of the electrolyte present in the container outside the housing during use. In this embodiment, reaction products obtained at the first electrodes cannot be migrated and converted back at one of the second electrodes. One or more membranes are each effective as a barrier to reaction products obtained at the first electrodes during use. This embodiment also potentially allows the use of different electrolytes having different compositions (e.g., cathode and anode). The selectively permeable membrane is then configured to form a barrier for at least one ionic species present in one of the electrolytes but not in the other. Thus, it is possible to include, for example, a catalyst (e.g., silver ions) in only one of the electrolytes. It is also possible to circulate only one of the electrolytes if, for example, this electrolyte contains a solution to be electrochemically regenerated (e.g., an etching solution containing manganese species to be electrochemically re-oxidized). The membrane can be permeable only to cations (e.g., hydrogen ions). Suitable membrane materials include, for example, Nafion (a sulfonated tetrafluoroethylene-based fluoropolymer copolymer).

[0065] Therefore, in a particular example of this embodiment, the housing is arranged to provide separation of the liquid inside the housing from the outside of the housing, except for at least one selective permeable membrane.

[0066] In an alternative embodiment of the apparatus, the array of first electrodes is at least partially surrounded by a housing arranged to provide separation of the liquid inside the housing from the outside of the housing, and at least one second electrode is attached to the housing, such that at least one section of each of the second electrodes is exposed to the inside of the housing.

[0067] In this case, it is possible for only one type of electrolyte to be present (for example, a circulating solution to be regenerated by electrochemical oxidation). Since the effective surface area of ​​the first electrode is much larger than the exposed surface of the second electrode, not all reaction products obtained at the first electrode are transferred to the second electrode, converted, and returned, especially when the electrolyte is circulated or otherwise passed through the inside of the housing. This embodiment has the further effect of keeping the volume inside the container available for the electrolyte relatively low compared to the volume of the first electrode and the effective surface area available at the first electrode. The housing can be a container or a container.

[0068] In any embodiment, the apparatus further includes a liquid conduction circuit including a pump for passing an electrolyte into the housing, the circuit including at least one inlet conduit and at least one outlet conduit extending out of the housing.

[0069] This embodiment is suitable for use, for example, in regenerating solutions such as etching solutions by electrochemically oxidizing at least one component of the solution, or for example, in removing plating from one or more components of a treatment solution. The circuit may include a reservoir. The circuit does not need to be closed. The inlet and outlet conduits may extend through further parts inside the container (e.g., further parts for housing at least one of at least one electrolytes) and through the walls of the container.

[0070] In an embodiment of the apparatus, at least one of the at least one end electrode is separated from the proximal of the at least one second electrode by a distance plate provided with a liquid-permeable window.

[0071] The window provides a path for current through at least one type of electrolyte between the first electrode and the second electrode. The distance plate allows the path to be relatively short without the risk of short circuit. The first and / or second electrodes can be relatively flexible. The distance plate keeps any such flexible parts apart even when faced with a pressure difference that could otherwise lead to contact due to one or more flexible parts bulging. In particular, the second electrode, the distance plate, and the first electrode can be assembled into a cell that forms a unit by mounting them together directly or via a support frame or housing.

[0072] In any embodiment, an array of first electrodes is at least partially enclosed by a housing, and second electrodes are located outside the housing, and the housing includes at least one selective permeable membrane that separates the inside of the housing from the outside of the housing. In examples in which this embodiment is combined, the at least one selective permeable membrane is located inside or above a window.

[0073] Therefore, it is possible to have a single membrane positioned on top of multiple windows, or individual membranes positioned within a window. In either case, the second electrode can be positioned particularly close to the array of the first electrodes, so that the reaction products formed at the first electrode do not reach the second electrode.

[0074] According to a second aspect, the first of the two objectives described above is solved by a method for performing an electrolytic process according to the present invention, characterized in that the step of causing current to flow includes establishing a potential at least on the main surface of the end electrodes that is different from the potential on the main surface of the first electrodes in the array other than the end electrodes, by making the potential of each of the second electrodes closer to the potential of the first electrodes.

[0075] This method can be used with the apparatus according to the first aspect of the present invention, for the reason that this apparatus may be suitable for using the method according to the second aspect of the present invention.

[0076] This method makes it possible to avoid causing very large currents to flow through the electrolyte via the primary surfaces of each end electrode that are oriented toward the second electrode. Instead, this current is made equal to the current flowing through the primary surfaces of the other first electrodes. The potential at least on the primary surfaces of the end electrodes is different from the potential on the primary surfaces of the first electrodes in the array other than the end electrodes at their corresponding locations. It is possible for a gradient to exist over any of the primary surfaces. The primary surfaces opposite any particular first electrode can, but do not need to be, at the same potential at their corresponding locations.

[0077] In an embodiment of the method, in addition to the end electrodes, the array of first electrodes includes at least two other first electrodes, and the step of causing current to flow includes establishing different potentials for each of the first electrodes on the main surface of these at least two other first electrodes, such that the difference in potential of the most proximal of the at least two second electrodes increases according to how much of the first electrode is spaced between the first electrode and the most proximal second electrode.

[0078] In this embodiment, it is possible to further equalize the respective currents flowing through each individual first electrode. In particular, they can all be reduced to a level where efficiency begins to decrease, or just below that level. If there are two second electrodes and the array of first electrodes is placed between the opposing surfaces of the second electrodes, then there will be two end electrodes in the array. This method then involves establishing a potential that increases from the end electrodes to one or two electrodes in the middle of the array and then decreases again on the main surface of the other first electrode. This is because, assuming a symmetrical arrangement with equal spacing between the second electrodes and each end electrode, the most proximal second electrode will be different for the first electrodes in one half of the array than for the first electrodes in the other half of the array. If there is only one second electrode, then there will be only one end electrode. Next, this method involves establishing a potential on the main surface of the other first electrodes, increasing from the end electrode to the first electrode at the opposite end of the array (which has the most first electrodes spaced between itself and the (only) end electrode). Again, it should be noted that a potential difference will exist between any two main surfaces of any one of the first electrodes. However, these will be smaller than if all the first electrodes were connected in parallel to each other and in series to a single current source.

[0079] In an embodiment of the method, the step of causing current to flow includes feeding separate currents between at least two current sources and each of the first electrodes in the array, which are independent of each other.

[0080] That is, separate currents are fed into only specific subsets of the first electrode, and these subsets are independent of each other. In set theory in mathematics and formal logic, two sets are said to be independent of each other if they have no common elements. One current is fed into only one of the independent subsets, further currents are fed into only another of the independent subsets, and so on.

[0081] These currents can be controlled to have specific respective values ​​using a controllable current source. Alternatively, the values ​​can be relatively uniform as a result of the configuration of the current source, the layout of the apparatus, and the electrolyte composition. As described above in the context of embodiments of similar apparatuses, one or more of the subsets can be formed by a single first electrode only. Using only multiple current sources, it is possible to implement the overall concept of establishing a potential at least on the main surface of the end electrodes that is different from the potential on the main surface of the first electrodes in the array other than the end electrodes. If this is done with respect to each first electrode in the array, in the case of a symmetrical arrangement with two second electrodes on either side of the array of first electrodes, each subset can include two first electrodes arranged symmetrically with respect to the middle of the array. Otherwise, generally, there will be one first electrode in each subset. Also, among other things, it is possible to have larger subsets when the overall concept behind the method is realized using pre-resistors. Each current source may include at least one voltage rectifier specific to that current source (i.e., not shared with other current sources). Alternatively, current sources may share voltage rectifiers but each have its own DC / DC converter, allowing for independent current supply to a subset of the first electrodes connected to that current source. For devices to be used in plants with DC current microgrids, voltage rectifiers are not required.

[0082] In an embodiment of the method, the step of causing current to flow includes feeding current between at least two of the first electrodes and a common current source via pre-resistors electrically positioned between the main surface of the first electrodes and a common current source, wherein the total resistance of the pre-resistors through which the current between the common current source and the first electrodes passes differs among the first electrodes connected to the common current source and decreases depending on how much of the first electrodes are spaced in the array between the first electrodes and the most proximal of at least one second electrode.

[0083] This is another way of realizing the concept of establishing a potential that is different at least at the main surface of the end electrodes from the potential at the main surface of the first electrodes in the array other than the end electrodes, by making the potential of each of the second electrodes closer to the potential of the end electrodes. In particular, this embodiment allows the potential to be different for each first electrode throughout the array without using a large number of separate current sources. This method can be implemented by a common current source configured or controlled only to supply a specific sum of current to all first electrodes connected to that common current source or to draw a specific sum of current from the first electrodes. Equalization between the individual first electrodes connected to the common current source is achieved by pre-resistors. As stated, this embodiment can be combined with embodiments using multiple separate current sources.

[0084] In this embodiment, the first electrodes, electrically connected in series with a common current source, are connected to each other in parallel circuits, and pre-resistors are placed in each branch of the parallel circuit in which the first electrodes are contained, such that the total resistance of the pre-resistors differs between the branches, and decreases depending on how much of the first electrodes are spaced in the array between the first electrode in the branch and the nearest of at least one second electrode.

[0085] Compared to alternative examples where pre-resistors interconnect consecutive first electrodes in an array, this embodiment is relatively easy to implement by using appropriate resistance values ​​for the pre-resistors.

[0086] The step of causing current to flow includes feeding current between at least two of the first electrodes and a common current source via a pre-resistor electrically positioned between the main surface of the first electrodes and a common current source, wherein the total resistance of the pre-resistor through which the current between the common current source and the first electrodes passes differs among the first electrodes connected to the common current source and decreases depending on how much of the first electrodes are spaced in the array between the first electrodes and the most proximal of at least one second electrode. In any example of the embodiment, the first electrodes are provided in the form of a sheet including at least one main section defining a main surface, the sheet forming at least one of the first electrodes further including at least one section, the at least one section forming one of the pre-resistors interconnecting the main section with at least one contact point, the at least one contact point electrically connecting the first electrode to the rest of the circuit in which the first electrode is contained.

[0087] Therefore, the pre-resistors are effectively integrated into the first electrode. This results in a compact arrangement that is relatively easy to manufacture. The sections forming one of the pre-resistors can be cut into the sheet, for example, in the form of a path from the contact point to the main section, and this path lies in the same plane when the sheet is arranged in a planar form. The term sheet is also used in the context of this embodiment simply to indicate that the lateral dimension of two opposing main surfaces is much greater than the thickness corresponding to the dimension between the two opposing main surfaces. The sheet can be permeable to liquids, does not need to have a rectangular shape, or can be flexible enough to be rolled up, for example.

[0088] The step of causing current to flow includes feeding current between at least two of the first electrodes and a common current source via pre-resistors electrically positioned between the main surface of the first electrodes and a common current source, wherein the total resistance of the pre-resistors through which the current between the common current source and the first electrodes passes differs among the first electrodes connected to the common current source, and decreases depending on how many of the first electrodes are spaced in the array between the first electrodes and the nearest of at least one second electrode. In an example of any embodiment of the method, the current is fed between the current source and the pre-resistor form, and current paths of different electrical resistances constituting each of the pre-resistors are formed within the pre-resistor form.

[0089] This example can be implemented without substantial modification to the existing first electrode design, other than providing a connection to a second electrical contact point. The pre-resistor formwork is generally a molded continuous mass of one or more electrically conductive materials. Suitable materials include, for example, titanium. This formwork does not need to be self-supporting and, in principle, can have any shape. This formwork can be formed, for example, by molding, cutting (e.g., laser cutting), milling, welding, soldering, or any combination thereof. Sections of the current path can be shared between current paths.

[0090] In this embodiment, the current is passed between the pre-resistor formwork and at least two electrical contact points of at least two of the first electrodes, each of which is electrically connected to a common current source via the pre-resistor, and which are spaced apart from each other.

[0091] This embodiment reduces the voltage difference across the main surface of the first electrode. Therefore, a more uniform distribution of current density exists between the electrolyte and its surfaces.

[0092] In an embodiment of the method, the array of first electrodes is at least partially enclosed by a housing, the second electrodes are located outside the housing, and the housing includes at least one selectively permeable membrane that separates the inside of the housing from the outside of the housing.

[0093] The housing can, for example, enclose the array of first electrodes up to the level of the electrolyte present in the container outside the housing during use. In this embodiment, the reaction products obtained at the first electrodes cannot be migrated and converted back at one of the second electrodes. This embodiment also potentially allows the use of different electrolytes having different compositions (e.g., cathode and anode). The selectively permeable membrane is then configured to form a barrier for at least one ionic species that is present in one of the electrolytes but not in the other. Thus, it is possible to include, for example, a catalyst (e.g., silver) in only one of the electrolytes, and to ensure that the reaction products generated at the first electrode are not converted back at one or more second electrodes (or vice versa). It is also possible to allow only one of the electrolytes to pass through the apparatus, for example, if this electrolyte contains a solution to be electrochemically regenerated (e.g., an etching solution containing manganese species to be electrochemically re-oxidized). The membrane can be permeable to cations only, for example. Suitable membrane materials include, for example, Nafion (a sulfonated tetrafluoroethylene-based fluoropolymer copolymer).

[0094] Therefore, in this embodiment, except for at least one selectively permeable membrane, the housing is arranged to provide separation of the liquid inside the housing from the outside of the housing. Thus, one of the first and second electrolytes can pass through the inside of the housing but not through the inside of the container outside the housing, or one of the first and second electrolytes can pass through the inside of the container outside the housing but not through the inside of the housing.

[0095] In another embodiment of the method, the array of first electrodes is at least partially surrounded by a housing arranged to provide separation of the liquid inside the housing from the outside of the housing, and at least one second electrode is attached to the housing, such that at least one section of each of the second electrodes is exposed to the inside of the housing.

[0096] In this case, it is possible for only one type of electrolyte to be present (for example, a solution pumped through the apparatus to be regenerated by electrochemical oxidation). Since the effective surface area of ​​the first electrode is much larger than the exposed surface of the second electrode, in particular, when the electrolyte is passed through the interior of the housing, not all of the reaction products obtained at the first electrode are transferred to the second electrode, converted, and returned. The interior of the container can have a relatively small volume available to accommodate the electrolyte. The remaining portion is essentially occupied by the first electrode.

[0097] In any embodiment of the method, in an example where (i) an array of first electrodes is at least partially enclosed by a housing, and second electrodes are located outside the housing, and the housing includes at least one selective permeable membrane that separates the interior of the housing from the outside of the housing, and apart from the at least one selective permeable membrane, the housing is arranged to provide separation of the liquid inside the housing from the outside of the housing; or (ii) an array of first electrodes is at least partially enclosed by a housing arranged to provide separation of the liquid inside the housing from the outside of the housing, and at least one second electrode is attached to the housing, and at least one section of each of the second electrodes is exposed to the interior of the housing, the method further includes the step of passing an electrolyte into the interior of the housing.

[0098] This embodiment is suitable for use, for example, in regenerating solutions such as etching solutions by electrochemically oxidizing at least one component of the solution, or for example, in removing plating from one or more components of a treatment solution. The step of passing the electrolyte through the inside of the housing may include, but is not required, a step of circulating the electrolyte.

[0099] In an example of any embodiment, the steps of providing at least one electrolyte into a container, in combination with passing an electrolyte into the interior of the housing, include providing a first electrolyte into the interior of the housing and providing a second electrolyte into the container outside the housing, wherein the array of first electrodes is at least partially enclosed by a housing, the second electrode is located outside the housing, and the housing includes at least one selective permeable membrane that separates the interior of the housing from the outside of the housing, and apart from the at least one selective permeable membrane, the housing is arranged to provide separation of the liquid inside the housing from the outside of the housing, and optionally, the steps of providing at least one electrolyte into a container in combination with passing an electrolyte into the interior of the housing include providing a first electrolyte into the interior of the housing and providing a second electrolyte into the container outside the housing, wherein the first and second electrolytes differ in terms of their composition.

[0100] This makes it possible to use a specific catalyst, for example, only in the electrolyte to which the first electrode is exposed. An example would be silver ions. Also, if one of the electrolytes is passed through the apparatus for the purpose of removing or regenerating its constituent materials, then naturally the other electrolytes do not need to contain those constituent materials.

[0101] In embodiments of the method, ions in at least one of at least one electrolyte (for example, ions containing manganese species) are electrolytically oxidized, for example, as a step in a process of at least partially regenerating the etching solution.

[0102] Such etching solutions are generally used in plating processes (e.g., those involving electroplating steps) to prepare nonmetallic surfaces. Etching solutions can be relatively acidic (e.g., containing phosphoric acid), which usually causes negatively charged manganese ions to revert to manganese oxide. The method of this embodiment allows this process to be reversed.

[0103] According to an independent third aspect, the second fundamental object of the present invention is realized by the electrode unit according to the present invention, characterized in that at least one of the electrodes is isolated from neighboring electrodes in the array by at least one spacer comprising a thread made of a material different from the conductive material, which passes through the electrode mesh as a sequence of stitches.

[0104] It is possible for two or more threads to exist. One or more threads can be arranged as a sequence of stitches that form a loop when viewed toward one of the main surfaces. The stitches can provide spacers with a relatively low contact area with the electrodes in many places. This is achieved relatively efficiently in that forming the stitches fixes the spacers in place. There is no need for further fasteners, nor is there a need to handle a large number of separate spacer elements. In this context, the mesh can be, for example, woven, braided, welded, sintered, etched, or electroformed. Thus, the strands of material constituting the mesh can be separate or intertwined, but do not have to be. They can simply be the result of forming a very large number of apertures within a sheet that forms the electrode precursor. In this context, the sheet is a formation with a transverse dimension, viewed perpendicular to one of the two opposing main surfaces of the sheet, which is much larger than the thickness between the two main surfaces. It should be noted that since the sheet contains the mesh, the effective surface area will be much larger than that defined by the transverse dimension.

[0105] The electrode unit may be for use in an apparatus according to a first aspect of the present invention and / or in a method according to a second aspect of the present invention.

[0106] The sheets can have a surface coefficient of, for example, 1 or more, such as 1.4 or more, 1.7 or more, or even 2, 2.2 or more, where the surface coefficient represents a parameter corresponding to the total effective surface area per geometric area. The thickness of each sheet can be on the order of micrometers, for example, in the range of 1 to 2 μm. The distance between sheets can be on the order of millimeters.

[0107] The thread can be a monofilament or can contain multiple filaments spun into a thread. The thread can have a diameter on the order of millimeters, for example, a diameter in the range of 0.5 to 5 mm, more specifically, a diameter in the range of 0.5 to 2 mm.

[0108] In the embodiment of the electrode unit, the thread material has a lower electrical conductivity than the conductive material.

[0109] Therefore, the threads are made from an electrically insulating material. A suitable material would be polyvinylidene difluoride. Threads made from an electrically insulating material are particularly suitable for use in the apparatus according to the first embodiment. This is because it not only allows the electrolyte to come into contact with a relatively high electrode surface area, but also allows the opposing main surfaces of neighboring electrodes to be electrically isolated from each other. Thus, they can be maintained at different electrical potentials.

[0110] In an example of the embodiment, where the thread material has a lower electrical conductivity than the conductive material, the electrode unit includes a plurality of current feeders for electrical connection to a separate current source located outside the electrode unit, the plurality of current feeders being electrically connected to a subset of electrodes in an array that are independent of each other, each subset including at least one of the electrodes.

[0111] Furthermore, this embodiment is particularly well suited for use in the apparatus according to the first embodiment. This is because this embodiment allows separate current sources to supply current to the electrodes and electrolyte. Thus, these current sources can be configured or actively controlled so that the current passing through the electrodes is more uniform across all electrodes in the array. This allows the apparatus containing the electrode unit to operate near the maximum current density, at which the yield begins to decrease significantly and the risk of excessive loss of certain surface coatings, such as platinum, begins to increase significantly.

[0112] In an example of any embodiment of the electrode unit, in which the thread material has a lower electrical conductivity than the conductive material, at least two of the electrodes are electrically connected in series with a common of at least one current feeder, and a pre-resistor is electrically positioned between the main surfaces of the electrodes electrically connected to the common current feeder, such that the total resistance of the pre-resistor between the common current feeder and the electrodes differs among the electrodes connected to the common current feeder and decreases in proportion to how many electrodes have been removed from the proximal end electrodes that terminate the array at either end.

[0113] Furthermore, this embodiment is particularly suitable for use in the apparatus according to the first embodiment. This is because this embodiment makes it possible to equalize the current through the electrodes even when the electrodes are connected to a common current source.

[0114] In this embodiment, the electrodes electrically connected in series with a common one of at least one current feeder are connected in parallel with respect to each other, and pre-resistors are placed in each branch of the parallel circuit in which the electrodes are contained, and the total resistance of the pre-resistors differs between the branches and decreases according to how many electrodes have been removed from the branch, starting from the nearest end electrode that terminates the array at either end.

[0115] In this embodiment, it is relatively easy to implement appropriate resistance values ​​for the pre-resistors. In an alternative example, the pre-resistors interconnect a series of electrodes connected to a common current feeder. The resistance of the path through the first electrode from one pre-resistor to the next must be taken into consideration.

[0116] In any example of the embodiment, the electrode sheet comprises at least one main section and at least one section, the at least one section forming one of the pre-resistors, and interconnecting the main section and at least one of the at least one electrical contact point. The material of the thread has a lower electrical conductivity than a conductive material, at least two of the electrodes are electrically connected in series with a common of at least one current feeder, and pre-resistors are electrically positioned between the main surfaces of the electrodes electrically connected to the common current feeder, and the total resistance of the pre-resistors between the common current feeder and the electrodes differs among the electrodes connected to the common current feeder, and decreases according to how many electrodes have been removed from the proximal end electrodes that terminate the array at either end.

[0117] Therefore, the pre-resistor is integrated into the electrode. This allows the electrode unit to be kept relatively compact. Moreover, it is relatively easy to provide pre-resistors with different resistance values. The assembly of the electrode unit is not very complex. The sections forming the pre-resistor can be provided by cutting differently shaped current paths into a mesh. The mesh can otherwise have the same configuration.

[0118] In any embodiment, the electrode unit is at least The present invention further includes a pre-resistor configuration, which provides at least one first electrical contact point electrically connected to one of at least one current feeders and a plurality of second electrical contact points, at least two of the second electrical contact points electrically connected to the contact points of each different electrode via one of a plurality of electrical conductors, and current paths of different electrical resistances are formed in the pre-resistor configuration between at least one of the at least one first contact point and the second contact points electrically connected to the contact points of each different electrode.

[0119] This example can be implemented without substantial modification to the existing electrode design, other than providing a connection to a second electrical contact point. The pre-resistor formwork is generally a molded continuous mass of one or more electrically conductive materials. Suitable materials include, for example, titanium and niobium. This formwork does not need to be self-supporting and, in principle, can have any shape. This formwork can be formed, for example, by molding, cutting (e.g., laser cutting), milling, welding, soldering, or any combination thereof. Sections of the current path can be shared between current paths.

[0120] In a particular example of this embodiment, the pre-resistor formation includes a sheet in which mutually separated current paths are formed, and the current paths of different electrical resistances differ in terms of at least one of length and cross-sectional area perpendicular to the direction of current path propagation along the length of the current path.

[0121] This embodiment is relatively easy to manufacture. The sheet can be self-supporting or can be supplied in the form of a foil on a support plate. The path can be obtained by cutting out its outline into the sheet (for example, by laser cutting). The term sheet in this context does not mean a specific outline. The precursor of the pre-resistor formwork can be a rectangular sheet or, more generally, have an outline prior to the formation of the current path which is a convex curve, although the process of forming the current path will generally result in the edges deviating from straight lines. However, the maximum lateral dimension will still be much larger than the thickness of the pre-resistor formwork.

[0122] The thread material has a lower electrical conductivity than the conductive material, at least two of the electrodes are electrically connected in series with a common of at least one current feeder, a pre-resistor is electrically positioned between the main surfaces of the electrodes electrically connected to the common current feeder, the total resistance of the pre-resistor between the common current feeder and the electrodes differs among the electrodes connected to the common current feeder and decreases according to how many electrodes are removed from the proximal end electrodes that terminate the array at either end, the electrode unit further includes at least one pre-resistor configuration, the pre-resistor configuration is small In any embodiment, the pre-resistor is provided with at least one first electrical contact point electrically connected to at least one of the current feeders, and a plurality of second electrical contact points, at least two of the second electrical contact points electrically connected to the contact points of each different electrode via each of the plurality of electrical conductors, and current paths of different electrical resistances are formed in the pre-resistor is configured between at least one of the first contact points and the second contact points electrically connected to the contact points of each different electrode, the pre-resistor is configured between two of the electrodes in the array.

[0123] Therefore, the electrode unit is relatively compact. The array is, in effect, a modified electrode stack.

[0124] The thread material has a lower electrical conductivity than the conductive material, at least two of the electrodes are electrically connected in series with a common of at least one current feeder, a pre-resistor is electrically positioned between the main surfaces of the electrodes electrically connected to the common current feeder, the total resistance of the pre-resistor between the common current feeder and the electrodes differs among the electrodes connected to the common current feeder and decreases according to how many electrodes have been removed from the proximal end electrodes that terminate the array at either end, the electrode unit further includes at least one pre-resistor configuration, the pre-resistor configuration is of at least one current feeder In any embodiment, the pre-resistor is provided with at least one first electrical contact point electrically connected to one and a plurality of second electrical contact points, at least two of the second electrical contact points being electrically connected to the contact points of each different electrode via one of the plurality of electrical conductors, and current paths of different electrical resistances are formed in the pre-resistor formation between at least one of the at least one first contact point and the second contact points electrically connected to the contact points of each different electrode, the pre-resistor formation is at least partially covered by a housing made of a material having a lower electrical conductivity than the material of the pre-resistor formation.

[0125] The housing is electrically insulating, and no leakage current is allowed from the pre-resistor set (for example, to an electrode with the opposite polarity to the electrode in the electrode unit). Therefore, the pre-resistor set can be partially or completely immersed in the electrolyte during use. The housing can, or does not need to, seal and enclose the pre-resistor set. A gap can, but does not need to exist, between the housing and the pre-resistor set, and covering does not necessarily mean that the surfaces of the two will touch each other.

[0126] In an embodiment of the electrode unit, at least one of a plurality of electrical conductors connecting one contact point of the electrodes passes through at least one other of the electrodes (for example, in a bushing that passes through at least one other electrode), and this bushing is made of a material having a lower electrical conductivity than the conductive material.

[0127] In an embodiment of the electrode unit, at least one of the electrodes includes at least two electrical contact points, which are spaced apart from each other.

[0128] This embodiment makes it possible to provide an electrode with a more uniform surface potential. It is possible to avoid locally excessive current density values ​​without excessively reducing the overall current passing through the electrode during use.

[0129] In embodiments of the electrode unit, the electrode includes at least one of lead, tantalum, platinum group metals, or their alloys or oxides (for example, at least one of platinum, platinum alloys, or platinum oxides) at least on its surface (for example, in the surface coating only).

[0130] Platinum group metals are particularly effective in charge transfer to catalysts such as silver ions in electrolytes, or directly to reagents. The cost of the electrode unit is reduced by providing the platinum group metal only on the electrode surface (for example, only in a surface coating). When provided as a surface coating, such a coating can have a thickness in the range of, for example, 0.5 μm to 2 μm. The thickness will be greater with respect to other materials, for example, in the range of 0.5 to 50 mm or 0.5 to 30 mm. The electrode unit is well suited for use in apparatus according to the first embodiment in which high current densities are very effectively avoided, so the electrode does not wear out too rapidly, even when, for example, the platinum group metal is provided only on the electrode surface.

[0131] In embodiments of the electrode unit, the mesh is primarily made from an inert material (for example, a material containing at least one of titanium, niobium, and carbon).

[0132] The electrode unit can be immersed in a relatively aggressive electrolyte. The electrode unit material does not participate in electrochemical reactions, increasing electrode lifetime and yield.

[0133] In embodiments of the electrode unit, at least one of the meshes is an expanded metal mesh.

[0134] Expanded metal is a type of sheet metal that has been cut and stretched to form apertures in a regular pattern. The apertures can be, for example, rhomboid or rhomboid in shape. These types of meshes are stronger than those formed from intertwined, separate strands.

[0135] The embodiment of the electrode unit further includes a housing that at least partially encloses the array of electrodes.

[0136] The housing protects the electrodes within the electrode unit and can also serve to separate different electrolytes (e.g., cathode liquid and anode liquid). Furthermore, the housing reduces the volume that needs to be filled by the electrolyte whose components react at the electrodes during use.

[0137] In any embodiment further including a housing that at least partially encloses the array of electrodes, the housing includes at least one selectively permeable membrane that isolates the interior of the housing from the exterior of the housing.

[0138] The housing can, for example, surround the array of electrodes up to the level of the electrolyte in which the electrode unit is at least partially immersed, in an apparatus in which the electrode unit is housed. In this embodiment, the reaction products obtained at the electrodes of the electrode unit cannot be migrated and converted back to the electrodes of the opposite polarity located outside the housing (or vice versa). This embodiment also potentially allows the use of different electrolytes having different compositions (e.g., cathode and anode). The selectively permeable membrane is then configured to form a barrier for at least one ionic species that is present in one of the electrolytes but not in the other. Thus, it is possible to include, for example, a catalyst (e.g., silver ions) in only one of the electrolytes. It is also possible to circulate only one of the electrolytes, for example, if this electrolyte contains a solution to be electrochemically regenerated (e.g., an etching solution containing manganese species to be electrochemically re-oxidized). The membrane can be permeable to cations only, for example. Suitable membrane materials include, for example, Nafion (a sulfonated tetrafluoroethylene-based fluoropolymer copolymer), but other options for membrane materials are also possible.

[0139] Therefore, in this embodiment, the housing is impermeable to liquids, except for at least one selectively permeable membrane.

[0140] In another example of any embodiment of the electrode unit, the electrode unit further includes a housing that at least partially encloses the array of electrodes, the housing being impermeable to liquid, and the electrode unit further includes at least one further electrode, the at least one further electrode being mounted on the housing, such that at least one section of the further electrode is exposed to the interior of the housing.

[0141] This results in a relatively compact electrolytic cell that can operate with a relatively small volume of electrolyte. The exposed sections of one or more additional electrodes have a much smaller surface area than the total effective surface area of ​​all electrodes in the electrode unit, simply because there are fewer additional electrodes present. However, it is possible for only selected sections of the additional electrodes to be exposed, and the rest to be shielded by either a housing or a separate shield.

[0142] The electrode unit further includes a housing that at least partially encloses the array of electrodes, wherein (i) the housing includes at least one selectively permeable membrane that separates the interior of the housing from the exterior of the housing, and the housing is impermeable to liquid except for the at least one selectively permeable membrane; or (ii) the housing is impermeable to liquid, and the electrode unit further includes at least one further electrode, the at least one further electrode being mounted on the housing, and at least one section of the further electrode being exposed to the interior of the housing. In any embodiment, the electrode unit further includes at least one liquid inlet and at least one liquid outlet for connecting the interior of the housing to an inlet conduit and an outlet conduit, respectively, to allow an electrolyte to pass through the interior of the housing.

[0143] This embodiment is suitable for use, for example, in regenerating solutions such as etching solutions by electrochemically oxidizing at least one component of the solution, or for example, in removing plating from one or more components of a treatment solution. An alternative example would be the electrochemical oxidation of an organic compound to purify an aqueous liquid.

[0144] According to a fourth aspect, the second fundamental object of the present invention is realized by an apparatus for performing an electrolytic process (for example, an apparatus according to a first aspect of the present invention), which is: A container for housing at least one electrolyte; and an electrode unit according to the present invention disposed within the container; With at least one second electrode located inside the container; A current supply system electrically connected to at least one current feeder of the electrode unit or to the second electrode is used to cause current to flow through at least one electrolyte to the second electrode and through the main surface of the electrode in the electrode unit. Includes.

[0145] In embodiments of the apparatus, the electrode unit further includes a housing that at least partially encloses an array of electrodes, wherein (i) the housing includes at least one selectively permeable membrane separating the interior of the housing from the exterior of the housing, and the housing is impermeable to liquid except for the at least one selectively permeable membrane; or (ii) the housing is impermeable to liquid, and the electrode unit further includes at least one further electrode, the at least one further electrode being mounted on the housing, such that at least one section of the further electrode is exposed to the interior of the housing. The electrode unit further includes at least one liquid inlet and at least one liquid outlet for connecting the interior of the housing to an inlet conduit and an outlet conduit, respectively, to allow an electrolyte to pass through the interior of the housing. The apparatus further includes a liquid conduction circuit including a pump for passing the electrolyte through the interior of the housing of the electrode unit.

[0146] The circuit may include a reservoir. The circuit does not need to be closed. Inlet and outlet conduits may extend through further parts inside the container (e.g., further parts for housing at least one of at least one electrolyte) and through the walls of the container.

[0147] Alternatively, the housing could be configured to function as a reservoir holding a stagnant amount of electrolyte to be processed in batches.

[0148] The present invention will be described in more detail with reference to the accompanying drawings. [Brief explanation of the drawing]

[0149] [Figure 1] This is a schematic diagram of the first apparatus for performing an electrolytic process, not to scale, or with all parts in the correct orientation. [Figure 2] This is a perspective view of a cell for the type of device schematically shown in Figure 1, with the cathode removed. [Figure 3] This is a detailed perspective view of the cell with most of the cell housing and the ducts connected to the housing removed. [Figure 4] Figures 2 and 3 show a first perspective view of the assembly of the support plate and pre-resistor plate contained within the cell. [Figure 5] This is a perspective view of the support plate on the opposite side of Figure 4. [Figure 6] This is a plan view of the pre-resistor plate on the support plate. [Figure 7] Figures 2-6 show perspective views of the two innermost electrodes within the electrode array contained in the cell. [Figure 8] Figures 2 to 7 show plan views of the mesh contained within the electrodes in the cells. [Figure 9] This is a detailed diagram of the mesh, also showing the spacers provided to the mesh. [Figure 10] Figures 2 to 9 are plan views of the contact points and integrated pre-resistors included in the usable electrodes in the cells. [Figure 11] Figures 2-9 are diagrams showing some of the resistor networks that can be used in the process of designing the pre-resistors for the cells. [Figure 12]This is a schematic diagram of a second apparatus for performing an electrolytic process, not to scale, or with all parts in the correct orientation. [Figure 13] Figure 12 is a perspective view of a cell for the type of device schematically shown. [Figure 14] Figure 13 is a perspective view of the cell without a cathode or electrical conductor bar connected to the cathode. [Figure 15] This is a perspective view of the electrode unit. [Figure 16] This is a detailed perspective view of the electrode unit. [Figure 17] This diagram corresponds to Figure 16, but shows the electrodes removed except for the end electrodes. [Figure 18] This is a plan view of the first alternative spacer configuration. [Figure 19] This is a plan view of the second alternative spacer configuration. [Modes for carrying out the invention]

[0150] A first apparatus 1 (Figure 1) for performing an electrolytic process includes a container 2 having a container interior 3. Distributed within the container interior 3 is an electrode unit 4, which includes an array of spaced-apart first electrodes, each first electrode including two end electrodes 5a, b and, in this simplified example, four further first electrodes 6a-d. Also distributed within the container interior 3 are two second electrodes 7a, b. The second electrodes 7a, b are arranged to have polarity opposite to that of the first electrodes 5a, b, 6a-d when in use. In the example to be discussed, the second electrodes 7a, b function as cathodes. The first electrodes 5a, b, 6a-d in the electrode unit 4 function as anodes.

[0151] Container 2 is provided with a filling opening 8 for filling most of the space inside the container 3 surrounding the electrode unit 4 with a first electrolyte (also referred to herein as cathode solution).

[0152] In the filled state of container interior 3, the second electrodes 7a and 7b are completely immersed in the cathode solution. This is because the second electrodes 7a and 7b are completely exposed to a portion of the container interior 3 surrounding the electrode unit 4.

[0153] The second electrode 7 is planar and has first main surfaces 9a and 9b having normals directed toward the electrode unit 4, and second main surfaces 10a and 10b having normals extending in the opposite direction. The first electrodes 5a, 5b and 6a-6d are also planar and have planes oriented generally parallel to the planes of the second electrodes 7a and 7b.

[0154] The first electrodes 5a, b, 6a-d are spaced between the second electrodes 7a, b. The end electrodes 5a, b have one main surface oriented toward the proximal one of the second electrodes 7a, b. Each of the end electrodes 5a, b is spaced between the proximal one of the two second electrodes 7a, b and all of the further first electrodes 6a-d and the other end electrode 5a, b. Each of the further first electrodes 6a-d has at least one of the end electrodes 5a, b spaced between them and the second electrodes 7a, b.

[0155] The first electrodes 5a, b, 6a-d each comprise a sheet in the form of a mesh made from an inert material (e.g., titanium, niobium, their alloys, or carbon). In certain embodiments, the mesh is an expanded metal mesh. The mesh can be coated with, for example, a layer of platinum.

[0156] The second electrodes 7a and 7b can be provided in the form of sheets, each containing a mesh. In an alternative embodiment, they can be provided in the form of solid plates. The second electrodes 7a and 7b can be made from an inert material (e.g., titanium, niobium, their alloys, or carbon). Alternatively, the second electrodes 7a and 7b can be made from stainless steel.

[0157] The liquid conduction circuit includes a pump 11 and a reservoir 12, and also includes an inlet conduit 13 connecting the pump 11 to a liquid inlet 14 of the housing 15 of the electrode unit 4, and an outlet conduit 16 leading from the liquid outlet 17 of the housing 15 back to the reservoir 12. Thus, the second electrolyte (also referred to herein as the anodic acid) can be passed through the housing 15 of the electrode unit 4.

[0158] The first and second electrolytes may differ in terms of their composition, including the properties and / or relative proportions of their constituent materials. In one example, both the first and second electrolytes contain phosphoric acid, but the second electrolyte additionally contains one or more further components (e.g., silver ions) that act as catalysts. The second electrolyte also contains a manganese species, which contains manganese oxide that is converted to a manganese species with a higher oxidation state (e.g., permanganate ions) as part of the process of regenerating the etching solution. The regenerated solution is collected in reservoir 12, which can be removed from reservoir 12 when in use.

[0159] The housing 15 of the electrode unit 4 includes at least one section containing one or more selective permeable membranes 18a, b that allow liquid to pass through but form a barrier against cations (or at least specific cation species). The selective permeable membranes 18a, b can, among other things, form a barrier against manganese species (e.g., manganese oxide and permanganate ions).

[0160] The current supply system includes a current source 19, which in this example includes a controllable current source. The current source 19 is positioned to be connected to a power grid (not shown) and therefore includes a rectifier 20. The current supply system is positioned to cause current to flow through the first and second electrolytes, as well as through an electrical circuit section 21 located outside the container 2, between the first electrodes 5a, b, 6a-d of the electrode unit 4 on the one hand and the second electrodes 7a, b on the other hand.

[0161] Since the current source 19 is controllable, the total current can be controlled to have a specific value. The first electrodes 5a, b, 6a-d are electrically connected to each other in parallel circuits, but are connected in series with the current source 19 via current feeders 22a, b that extend from the electrode unit 4 into a portion of the container interior 3 surrounding the electrode unit 4. The individual currents through the first electrodes 5a, b, 6a-d of the electrode unit 4 are not controlled separately, but their relative values ​​are determined by pre-resistors (not shown in Figure 1) placed in each branch (not necessarily all branches) of the parallel circuit in which the first electrodes 5a, b, 6a-d are contained. The resistance values ​​of the pre-resistors differ between branches, for example, decreasing depending on how many of the first electrodes are spaced between the first electrode in the branch and the nearest of the second electrodes 7a, b. Thus, the pre-resistor values ​​will be highest with respect to the end electrodes 5a, b and will decrease towards the middle of the array. Due to the presence of additional first electrodes 6b,c in the center of the array, a pre-resistor may not be present.

[0162] Although not shown in Figure 1, the second electrodes 7a and 7b are mounted in the housing 15 of the electrode unit 4, making it possible to form a cell for immersion within the container interior 3. Thus, the container interior 3 can have a relatively small volume. This is particularly useful when the apparatus 1 is used to convert manganese species to manganese species with a higher oxidation state, because the latter tends to revert relatively quickly to species with a lower oxidation state.

[0163] An example of such a cell 23 (Figures 2-10) (shown here with the second electrode removed) includes a housing 24 (Figure 2). The housing 24 encloses, at least partially (in this example, only partially) an electrode unit 25 (Figure 3). The electrode unit 25 includes a first electrode array 26, which consists of first electrodes electrically isolated from one another. The description of the electrode unit 4 given above with reference to Figure 1 also applies to the electrode unit 25 and the first electrode array 26 of the cell 23.

[0164] Therefore, the housing 24 is provided with a liquid inlet 27 for connecting the inside of the housing 24 to the inlet conduit 28. The housing 24 is also provided with a liquid outlet 29 for connecting the inside of the housing 24 to the outlet conduit 30. This allows the electrolyte (e.g., anolyte) to pass through the inside of the housing 24 in the manner described above in relation to the first apparatus 1.

[0165] The housing 24 is impermeable to liquid but is open at the opposite end, where distance plates 31a and 31b are provided with liquid-permeable windows (Figure 2). In one embodiment, each selective permeable membrane is positioned within its respective window. In another embodiment, the selective permeable membrane is fitted to the distance plates 31a and 31b in a sealed manner to cover the liquid-permeable windows.

[0166] In the illustrated embodiment, the distance plates 31a,b are contained within the electrode unit 25 and mounted on the first electrode array 26 in close proximity to the end electrodes at the opposite end of the first electrode array 26. A circumferential seal is provided between each distance plate 31a,b and the housing 24, providing separation of the liquid between the inside and outside of the housing 24 (i.e., the space around the housing 24).

[0167] As illustrated, and similar to the first apparatus 1, two current feeders 32a,b extend through the housing 24. A seal ensures that the separation of liquid between the inside and outside of the housing 24 is maintained in this location as well. The current feeders 32a,b can be made of, for example, copper or another type of electrically conductive material. The current feeders 32a,b are placed in liquid-impermeable ducts, which can isolate the cells 23 from the electrolyte in which they are immersed during use. The current feeders 32a,b are configured to electrically connect the first electrode array 26 (in this case, each of the first electrodes contained therein) to a current supply located outside the electrode unit 25.

[0168] Similar to the first apparatus 1, cell 23 is configured such that, when connected to the current supply, the resulting apparatus establishes different potentials for each first electrode on the main surface of the first electrodes in the first electrode array 26, such that the potential difference with respect to the most proximal second electrode of cell 23 increases according to how much of the first electrodes are spaced between the first electrode and the most proximal second electrode. This is again achieved by pre-resistors having increasing resistance values ​​from one first electrode to the next end electrode, starting at the center of the first electrode array if two second electrodes are present, or starting at the most distal first electrode if only one second electrode is present.

[0169] In the illustrated embodiment, the pre-resistor is integrated into the pre-resistor formwork 33, which is cut from foil and applied to support plates 34a, b (Figures 4-6). In the illustrated embodiment, two such assemblies exist. They are arranged symmetrically and connected to both current feeders 32a, b, respectively, at the first electrical contact points 35a, b. The support plates 34a, b can be made from an electrically insulating material having a lower electrical conductivity than the material of the pre-resistor formwork. In the illustrated embodiment, an additional foil of a material having a lower electrical conductivity than the pre-resistor formwork 33 is applied to the other side of the pre-resistor formwork 33, forming a housing made from the material having an even lower electrical conductivity. The materials of the additional foil and support plates 34a, b do not have to be the same.

[0170] Current paths 36a to n are formed within the pre-resistor forming body. Current paths 36a to n are formed between the first electrical contact points 35a and 35b and the respective second electrical contact points 37a to n. Each second electrical contact point 37 is connected to one of the first electrodes in the first electrode array 26. The electrical resistance of the current path 36 varies depending on which first electrode the second electrical contact point 37 is connected to.

[0171] In the illustrated embodiment, current paths 36a-n differ in terms of length and cross-sectional area. Here, the cross-sectional area is the area of ​​the cross-section perpendicular to the direction of propagation along the length of the path (i.e., along the neutral axis of the path). Since they are cut from foil, current paths 36a-n are of the same height. Certain current paths 36b, c, e, f, i, j, l, m include at least one meandering section, which means that the direction of propagation along the length of the path changes relatively frequently. Certain current paths 36a, d, g, h, k, n are straight. The length, profile, and cross-section of current paths 36a-n determine their resistances.

[0172] It is clear that the current feeders 32a and 32b, as well as the assembly of the support plate 34 and the pre-resistor forming body 33, are spaced in the center of the first electrode array 26, between the central first electrodes 38a and 38b (Figure 7).

[0173] The second electrical contact points 37a-n are electrically connected to the pair of first electrodes (one on either side of the pre-resistor formwork 33a, b) by electrical conductors in the form of bolts or rods with threads provided at both ends. In the case of the central first electrodes 38a, b, the electrical conductor passes only through these central first electrodes 38a, b. Nuts and discs clamp the electrical conductor to the central first electrodes 38a, b. In the illustrated embodiment, there are two conductors, which are clamped to the respective central first electrodes 38 at contact points 39a, b, spaced apart in the plane of the central first electrodes 38a, b.

[0174] The electrical conductors interconnecting the second electrical contact points 37a-c, e-j, l-n to the other first electrodes are of different lengths and pass through the first electrodes spaced between the pre-resistor forms 33a, b and the first electrodes to which they are connected. To avoid short circuits, such electrical conductors are placed within bushings 40a-l made of an electrically insulating material. Again, nuts and discs are provided at the ends of the electrical conductors to hold the first electrodes at the spaced-out electrical contact points.

[0175] In addition, there are further bolts or rods with threaded ends, along which an array of discs 41a-d is provided. These discs of arrays 41a-d are made of an electrically insulating material. These assemblies serve only to hold the first electrodes, and the discs of arrays 41a-d act as spacers interposed between neighboring first electrodes in the first electrode array 26.

[0176] Referring to the exemplary first electrode 42 (Figures 8 and 9), at least one thread 43a,b of the electrically insulating material is passed through a mesh forming the electrode in the form of a sequence of stitches 44a to e. In the illustrated embodiment, a sequence path 45a in the periphery of the exemplary first electrode 42 extends along this periphery. Further sequence paths 45b,c extend across the plane defined by the exemplary first electrode 42.

[0177] Threads 43a and 43b can be monofilament threads or multifilament threads. A suitable material is polyvinylidene difluoride.

[0178] It is possible to understand that the exemplary first electrode 42 is provided with a number of apertures 46a-l through which the bushing 40 can pass, and two spaced-apart electrical contact points 47a, b.

[0179] In addition to providing pre-resistors as integral parts of pre-resistor forms 33a,b, it is alternatively or additionally possible to integrate pre-resistors into one or more of the electrodes in the first electrode array 26. In that case, the sheet forming one of the first electrodes includes at least one main section 48 and a pre-resistor section 49, where only a portion of at least one main section 48 is shown (Figure 10), the pre-resistor section 49 forms one of the pre-resistors, interconnecting the main section 48 with at least one of the electrode contact points 50, the electrode contact point 50 electrically connecting the first electrode to the rest of the branch of the parallel circuit in which the first electrode is contained. In the illustrated embodiment (Figure 10), the first electrode is made from expanded metal. The pre-resistor section 49 includes a meandering path, the outline of which is cut into a mesh of expanded metal (e.g., laser cut). The basic shape of this path is a spiral around the electrode contact point 50, with the path having a superimposed undulating shape due to the basic grid shape of the mesh from which it is cut. The electrical resistance can be easily set during manufacturing by selecting an appropriate length for the spiral.

[0180] A method for selecting an appropriate pre-resistor value involves modeling the first device 1. The model includes a model current source 51 (Figure 11). The model also includes a cathode resistor R representing the electrical resistance of the second electrode (in this case, the cathode). c It further includes the resistance R representing the electrical resistance of the second electrode. c In particular, the electrolyte into which the second electrode is immersed during use functions as a coolant, so it is interpreted as a fixed value. Cathode liquid resistance R cl R represents the electrical resistance of the current path from the electrolyte in which the second electrode is immersed to the membrane separating the electrolyte from which the first electrode of the array of first electrodes is immersed. clThe value of m is variable but can be taken from the current-potential curve for the electrolyte. The model further includes a membrane resistance R m which represents the electrical resistance encountered by the current passing through the membrane between the electrolyte in which the second electrode is immersed and the electrolyte in which the first electrode is immersed. The value of the membrane resistance R m can be interpreted as being fixed. This value can be calculated from the values of the membrane dimensions and conductivity. The model further includes a first anolyte resistance R ma1 which represents the electrical resistance of the current path through the electrolyte in which the first electrode is immersed, from the membrane to one of the end electrodes. The value of the first anolyte resistance R ma1 is fixed. This value can be calculated from the electrolyte resistivity, path length, and cross-sectional areas of the end electrodes and the membrane. Then there is a first first electrode electrolyte resistance R ma1 which represents the electrical resistance of the current path through the electrolyte in which the first electrode is immersed, from one major surface of the end electrode to the opposite major surface. It is recalled that the first electrode includes a sheet in the form of a mesh through which this current path exists. The first first electrode electrolyte resistance R a1 is again fixed. Also, the model includes a front surface resistance R a1 and a back surface resistance R a1 for the first end electrode. The values of these resistances are variable depending on the reactions at these surfaces. Their values can be calculated from the current-potential curve for the electrolyte in which the first electrode is immersed. f1 and a back surface resistance R b1 including. The values of these resistances are variable depending on the reactions at these surfaces. Their values can be calculated from the current-potential curve for the electrolyte in which the first electrode is immersed.

[0181] Similar to the end electrode, the next first electrode in the array has a second first electrode resistance R a2 , a front surface resistance R f2 , and a back surface resistance R b2It can be modeled by, and similarly, the other end electrode and the second electrode can also be modeled. The resistance network, in particular the nonlinear current-potential relationship with respect to the electrolyte on the surface of the first electrode, and Kirchhoff's laws generate a system of nonlinear equations, which can be solved, for example, using a least-squared deviation fit solving strategy.

[0182] To obtain an appropriate resistance value for the pre-resistor, the pre-resistor resistance value R pre1 , R pre2 However, this is added to the model at the branch representing the first electrode. The current through each of the first electrodes is calculated by solving a system of nonlinear equations modified to reflect the added pre-resistors. This is repeated iteratively until an acceptable uniformity in the values ​​is achieved.

[0183] To simplify calculations, values ​​for symmetrical devices, such as the first device 1, can be obtained by modeling only half of the device, up to the center of the array of first electrodes. It is also possible to add only one pre-resistor, i.e., the pre-resistor value R for the end electrodes. pre1 It is possible to include only that.

[0184] A second apparatus 52 (Figure 12) for performing the electrolytic process includes a container 53 having a container interior 54. Distributed within the container interior 54 is an electrode unit 55, which includes an array of spaced-apart first electrodes, the first electrodes including two end electrodes 56a, b and, in this simplified example, six further first electrodes 57a-f. Also distributed within the container interior 54 are two second electrodes 58a, b. The second electrodes 58a, b are arranged to have polarity opposite to that of the first electrodes 56a, b, 57a-f when in use. The description of the second apparatus 52 will proceed on the basis that the second electrodes 58a, b function as cathodes. The first electrodes 56a, b, 57a-f in the electrode unit 55 function as anodes.

[0185] The container 53 is provided with a filling opening 59 for filling most of the space inside the container 54 surrounding the electrode unit 55 with a first electrolyte (also referred to herein as cathode solution).

[0186] When the container interior 54 is filled, the second electrodes 58a and 58b are completely immersed in the cathode solution. This is because the second electrodes 58a and 58b are completely exposed to a portion of the container interior 54 surrounding the electrode unit 55.

[0187] The second electrode 58 is planar and has first main surfaces 60a, b having normals directed toward the electrode unit 55, and second main surfaces 61a, b having normals extending in the opposite direction. The first electrodes 56a, b, 57a-f are also planar and have planes oriented generally parallel to the planes of the second electrodes 58a, b.

[0188] The first electrodes 56a, b, 57a-f are spaced between the second electrodes 58a, b. The end electrodes 56a, b have one main surface oriented toward the proximal one of the second electrodes 58a, b. Each of the end electrodes 56a, b is spaced between the proximal one of the two second electrodes 58a, b and all of the further first electrodes 57a-f and the other end electrode 56a, b. Each of the further first electrodes 57a-f has at least one of the end electrodes 56a, b spaced between them and the second electrodes 58a, b.

[0189] The first electrodes 56a, b, 57a-f each comprise a sheet in the form of a mesh made from an inert material (e.g., titanium, niobium, their alloys, or carbon). In certain embodiments, the mesh is an expanded metal mesh. The mesh can be coated, for example, with a layer of platinum.

[0190] The second electrodes 58a and 58b can be provided in the form of sheets, each containing a mesh. In an alternative embodiment, they can be provided in the form of solid plates. The second electrodes 58a and 58b can be made from an inert material (e.g., titanium, niobium, their alloys, or carbon). Alternatively, the second electrodes 58a and 58b can be made from stainless steel.

[0191] The liquid conduction circuit includes a pump 62 and a reservoir 63, and also includes an inlet conduit 64 connecting the pump 62 to a liquid inlet 65 of the housing 66 of the electrode unit 55, and an outlet conduit 67 leading from the liquid outlet 68 of the housing 66 back to the reservoir 63. Thus, the second electrolyte (also referred to herein as the anodic acid) can be passed through the housing 66 of the electrode unit 55.

[0192] The first and second electrolytes may differ in terms of their composition, including the properties and / or relative proportions of their constituent materials. In one example, both the first and second electrolytes contain phosphoric acid, but the second electrolyte additionally contains silver ions that act as a catalyst. The second electrolyte also contains manganese species, which include manganese oxide, which is converted to manganese species with a higher oxidation state (e.g., permanganate ions) as part of the process of regenerating the etching solution. The regenerated solution is collected in reservoir 63, which can be removed from reservoir 63 when in use.

[0193] The housing 66 of the electrode unit 55 includes at least one section containing one or more selectively permeable membranes 69a, b that allow liquid to pass through but form a barrier against cations (or at least specific cation species).

[0194] The current supply system includes a plurality of current sources 70a to d. In the simplified illustrated embodiment, there are four current sources 70a to d. In the illustrated embodiment, the current sources 70a to d are controllable current sources.

[0195] Each of the current sources 70a to d is electrically connected in series to each pair of first electrodes 56a, b, and 57a to f via their respective current feeders 71a to d. Each of the first electrodes 56a, b, and 57a to f is connected to only one of the current sources 70a to d, so that the first electrodes 56a, b, and 57a to f form mutually independent subsets of the complete set of first electrodes 56a, b, and 57a to f. Each subset contains two first electrodes 56a, b, and 57a to f. A pair of first electrodes 56a, b, and 57a to f are electrically connected to each other in parallel circuits but in series with the current source 70. In the illustrated embodiment, the electrodes in the subset are arranged symmetrically with respect to the center of the array of first electrodes 56a, b, and 57a to f. This is not necessarily the case in variations of the illustrated embodiment.

[0196] The current sources 70a to d are arranged to be connected to a power grid (not shown) and therefore each includes a rectifier 72a to d. The current supply system is arranged to cause current to flow between the first electrodes 56a, b, 57a to f of electrode unit 55 on the one hand and the second electrodes 58a, b on the other hand, through the first and second electrolytes, as well as through a common electrical circuit section 73 located outside the container 53.

[0197] The current sources 70a to d are set such that the currents flowing through the first electrodes 56a, b, and 57a to f are slightly different or not different at all. This means that the current sources 70a to d establish different potentials for each of the first electrodes on the main surface of the first electrodes 56a, b, and 57a to f, so that the difference in potential of the most proximal of the two second electrodes 58a and b increases according to how much of the first electrodes 56a, b, and 57a to f are spaced between the first electrode of interest and the most proximal second electrode 58a and b. Thus, the same effect is achieved as in the first apparatus 1, but without the use of pre-resistors.

[0198] The two methods for achieving this effect can be combined when the current supply sources 70a to d are not connected in series to a pair of first electrodes 56a, b, 57a to f that are symmetrically arranged with respect to the center of the array of first electrodes 56a, b, 57a to f.

[0199] Although not shown in Figure 12, the second electrodes 58a and 58b are mounted in the housing 66 of the electrode unit 55, making it possible to form a cell for immersion within the container interior 54. Thus, the container interior 54 can have a relatively small volume.

[0200] Examples of such cells 74 (Figures 13-17) are configured for use in an apparatus for performing an electrolytic process (e.g., a second apparatus 52).

[0201] Cell 74 includes a housing 75. The housing 75 encloses, at least partially (in this example, only partially) an electrode unit 76 (Figure 15). The electrode unit 76 includes a first electrode array 77, which consists of first electrodes that are electrically isolated from one another.

[0202] The first electrode array 77 includes two end electrodes 78a, b, one at each end of the first electrode array 77. Further first electrodes are interposed between the end electrodes 78a, b. Each first electrode in the first electrode array 77 is provided in the form of a liquid-permeable sheet, which in this example includes a mesh (e.g., expanded metal mesh). The first electrodes can contain at least one of lead, tantalum, platinum group metals, or alloys or oxides thereof, at least on their surface (e.g., only in the surface coating). In one example, the surface coating is provided on a wire made of an inert metal (e.g., titanium, niobium, or carbon).

[0203] An identical second electrode assembly (Figure 13) is provided on the opposite side of cell 74 (only one side is shown). These each contain a second electrode sheet 79 (for example, in the form of a mesh) in this example. The second electrode sheet 79 can be made from an inert material (for example, titanium, niobium, an alloy thereof, or carbon) or stainless steel.

[0204] During use, each second electrode sheet 79 is connected to a current supply source such as the current supply sources 70a to d of the second device 52.

[0205] The housing 75 is provided with a liquid inlet 80 for connecting the inside of the housing 75 to an inlet conduit 81. The housing 75 is also provided with a liquid outlet 82 for connecting the inside of the housing 75 to an outlet conduit 83. This allows an electrolyte (e.g., an anode liquid) to pass through the inside of the housing 75 in the manner described above in relation to the second apparatus 52.

[0206] The housing 75 is impermeable to liquids but is open at opposite ends. At each end, the housing 75 forms an opening, and a liquid-permeable spacer plate 84 (Figure 14) is sealed and positioned within or opposite the opening. The spacer plate 84 is made of an electrically insulating material. In the illustrated embodiment, the spacer plate 84 provides empty windows. In the illustrated embodiment, the windows are of equal size and shape and are arranged in a regular grid.

[0207] Cell 74 includes six current feeders 85a-f (Figure 15) for series connection to separate current sources (not shown), in the manner described with reference to the second apparatus 52. The current feeders 85a-f extend through the housing 75. Seals ensure that the separation of liquid between the inside and outside of the housing 75 is maintained in this location as well. The current feeders 85a-f are placed in liquid-impermeable ducts, making it possible to isolate the cell 74 from the electrolyte in which it is immersed during use.

[0208] Each current feeder 85 is connected to two first electrodes in the first electrode array 77 by electrically conductive sheets 86a-f and electrically conductive distance sheets 87a,b. The sheets 86a-f, 87a,b can be made from inert materials (for example, titanium, niobium, their alloys, or carbon).

[0209] In one embodiment, the first electrodes in the first electrode array 77 are separated by spacer disk arrays 88a-g, and bolts in electrically insulating bushings pass through the spacer disk arrays 88a-g. It will become clear that a relatively large number of these arrangements are required.

[0210] Alternatively or additionally, spacer strips 89 (Figure 18) can be placed between neighboring first electrodes in the first electrode array 77. These extend over at least a large portion of the maximum dimension (in this case, height) of the first electrodes. Only three bolts in the bushing are required to secure each spacer strip 89 in place, but they cover a relatively large area.

[0211] Another alternative is the use of spacer grids 90a, b (Figure 19) (in this example, two overlapping spacer grids 90).

[0212] Alternatively or additionally, spacers in the form of threads of an electrically insulating material can be used in the same manner as the threads 43a-c of the cell 23 in embodiments with pre-resistors. In that case, bolts are required only to fix the first electrodes of the first electrode array 77 and not to fix the spacers. Furthermore, less electrode surface is covered by the spacers, and the flow of electrolyte through the electrodes is relatively less obstructed compared to spacer strips 89 or spacer grids 90.

[0213] In all cases, spacers and bushings made from electrically insulating materials can be made from polyvinylidene difluoride, polytetrafluoroethylene, or other types of fluorinated polymer materials. This also applies, for example, to the distance plates 31a-f of cell 23 and the spacer plate 84 of cell 74. Metal parts coated with polymers to make them electrically insulating (this applies, for example, to the parts of housing 75) can be coated with polymers such as ethylene-chlorotrifluoroethylene (trade name: Halar).

[0214] Neighboring first electrodes in the first electrode array 77 are electrically isolated from each other and provided with separate current sources, so that the potentials at corresponding locations on the main surface of the first electrodes can be different, and the values ​​of the current passing through them can be more uniform than otherwise. These values ​​can all be set near the level at which the reaction yield begins to plateau and / or the level at which the risk of high wear on the surface becomes considerably higher.

[0215] The spacers in the form of threads 43a-c allow for the use of a relatively large number of thin, closely positioned first electrodes while keeping the effort and number of parts required to manufacture the first electrode array 26;77 within a reasonable range.

[0216] The present invention is not limited to the embodiments described above, and can be modified within the scope of the appended claims. For example, the electrical conductor connecting the first electrode to the pre-resistor forming body 33 may have different electrical resistances and therefore may function as a pre-resistor. [Explanation of Symbols]

[0217] 1. First apparatus 2 containers 3 Inside the container 4 electrode units 5a,b End electrode 6a~d Further first electrodes 7a, b Second electrode 8 Filling opening 9a,b First main surface 10a, b Second main surface 11 pumps 12 Reservoirs 13 Inlet conduit 14 Liquid inlet 15 Electrode Unit Housing 16 Outlet conduit 17 Liquid outlet 18a,b membrane 19 Current supply source 20 Rectifier 21 External Electrical Circuit Section 22a, b Current feeder 23 cells 24 Housing 25 Electrode Units 26 First electrode array 27 Liquid inlet 28 Inlet conduit 29 Liquid outlet 30 Outlet conduit 31a, b Distance Plate 32a, b Current feeder 33 Pre-resistor formation body 34a, b Support plate 35a, b First electrical contact point 36a~n Current path 37a~n Second electrical contact point 38a, b Central first electrode 39a, b Electrode contact points 40a~l Bushing 41a~d Disk Array 42 Exemplary first electrode 43a, b threads 44a~e Stitch 45a~c Sequence pathway 46a-l Bushing Aperture 47a, b Exemplary electrode contact points 48 Main Sections 49 Pre-resistor section 50 Contact Points 51 Model Current Sources 52 Second device 53 containers 54 Inside the container 55 electrode units 56a,b End electrode 57a~f Further first electrodes 58a, b Second electrode 59 Filling opening 60a,b First main surface 61a, b Second main surface 62 pumps 63 Reservoir 64 Inlet conduit 65 Liquid inlet 66 Housing 67 Outlet conduit 68 Liquid outlet 69a,b membrane 70a~d Current supply source 71a~d Current feeder 72a~d Rectifier 73 External Electrical Circuit Section 74 cells 75 Housing 76 Electrode Units 77 First electrode array 78a,b End electrode 79 Second electrode sheet 80 Liquid inlet 81 Inlet conduit 82 Liquid outlet section 83 Outlet conduit 84 Spacer Plate 85A~F Current Feeder 86a~f Electrically conductive sheets 87a, b Distance Sheet 88a~g Spacer disk array 89a, b Spacer strip 90a, b Spacer grid

Claims

1. An apparatus for performing an electrolytic process, wherein the apparatus is A container (2;53) having an interior (3;54) for containing at least one type of electrolyte; An array (26; 77) of first electrodes (5a, b, 6a-d; 38a, b, 42; 56a, b, 57a-f; 78a, b) spaced apart and placed inside the container (2; 53); At least one second electrode (7a, b; 58a, b; 79), wherein at least a portion of the surface of the at least one second electrode (7a, b; 58a, b; 79) is positioned such that at least a portion of its surface is exposed to at least a portion of the inside of the container (3; 54) for containing at least one of the at least one electrolytes; A current supply system for causing current to flow through the second electrode (7a, b; 58a, b; 79) and the main surface of the first electrode (5a, b; 6a-d; 38a, b; 42; 56a, b; 57a-f; 78a, b) by establishing a potential difference between the main surface of the first electrode (5a, b; 6a-d; 38a, b; 42; 56a, b; 57a-f; 78a, b) on the one side and the second electrode (7a, b; 58a, b; 79) on the other side, such that the first electrode (5a, b; 6a-d; 38a, b; 42; 56a, b; 57a-f; 78a, b) has polarity opposite to that of the second electrode (7a, b; 58a, b; 79), and Includes, The array (26; 77) of the first electrodes (5a, b, 6a-d; 38a, b, 42; 56a, b, 57a-f; 78a, b) includes at least one end electrode (5a, b; 56a, b; 78a, b) spaced between one of the second electrodes (7a, b; 58a, b; 79) on the one hand and all of the other first electrodes (6a-d; 38a, b, 42; 57a-f) of the array (26; 77) on the other hand. In addition to the end electrodes (5a, b; 56a, b; 78a, b), the array of first electrodes (26; 77) includes at least one first electrode other than the end electrodes (6a-d; 38a, b; 42; 57a-f) in the apparatus, The apparatus is characterized in that it is configured to establish a potential at least on the main surface of the end electrodes (5a, b; 56a, b; 78a, b) that is different from the potential on the main surface of the first electrodes (6a-d; 38a, b, 42; 57a-f) in the array (26; 77) other than the end electrodes (5a, b; 56a, b; 78a, b) by making it close to the potential of each of the second electrodes (7a, b; 58a, b; 79).

2. The apparatus according to claim 1, wherein the current supply system includes at least two current sources (70a to d), each of the at least two current sources (70a to d) being electrically connected in series to each independent subset of the first electrodes (56a, b, 57a to f; 78a, b) in the array (77) via their respective current feeders (71a to d; 85a to f).

3. At least two of the first electrodes (5a, b, 6a-d; 38a, b, 42) are electrically connected in series with a common current source (19) included in the current supply system. The pre-resistor is electrically positioned between the main surfaces of the first electrodes (5a, b, 6a-d; 38a, b, 42) which are electrically connected to the common current source (19). The apparatus according to claim 1 or 2, wherein the total resistance of the pre-resistors between the common current source (19) and the first electrodes (5a, b, 6a-d; 38a, b, 42) differs among the first electrodes (5a, b, 6a-d; 38a, b, 42) connected to the common current source (19), and decreases in proportion to how many of the first electrodes (5a, b, 6a-d; 38a, b, 42) are spaced apart in the array (26) between the first electrodes (5a, b, 6a-d; 38a, b, 42) and the closest of the at least one second electrode (7a, b).

4. The apparatus according to claim 3, wherein the first electrodes (5a, b, 6a-d; 38a, b, 42), which are electrically connected in series with a common current source (19), are connected to each other in parallel circuits, and the pre-resistors are placed in each branch of the parallel circuit containing the first electrodes, and the total resistance of the pre-resistors differs between the branches, and the distance between the first electrodes (5a, b, 6a-d; 38a, b, 42) in the branch and the nearest of the at least one second electrode (7a, b) decreases according to the number of first electrodes (5a, b, 6a-d; 38a, b, 42) spaced in the array (26).

5. The first electrodes (5a, b, 6a-d; 38a, b, 42) are provided in the form of a sheet including at least one main section (48) defining the main surface, The apparatus according to claim 3 or 4, wherein the sheet forming at least one of the first electrodes (5a, b, 6a-d; 38a, b, 42) further comprises at least one section (49), the at least one section (49) forming one of the pre-resistors, interconnecting the main section (48) with at least one contact point (50), the at least one contact point (50) electrically connecting the first electrodes (5a, b, 6a-d; 38a, b, 42) to the rest of the circuit comprising the first electrodes (5a, b, 6a-d; 38a, b, 42).

6. The apparatus further includes at least one pre-resistor forming body (33), The pre-resistor forming body (33) is provided with at least one first electrical contact point (35a, b) that is electrically connected to a current supply source (19) included in the current supply system, and a plurality of second electrical contact points (37a to n). At least two of the second electrical contact points (37a to n) are electrically connected to different first electrodes (5a, b, 6a to d; 38a, b, 42), The apparatus according to any one of claims 3 to 5, wherein current paths (36a to n) of different electrical resistances are formed in the pre-resistor forming body (33) between at least one of the at least one first electrical contact points (35a, b) and second electrical contact points (37a to n) that are electrically connected to different first electrodes (5a, b, 6a to d; 38a, b, 42).

7. The apparatus according to claim 6, wherein each of the first electrodes (5a, b, 6a-d; 38a, b, 42) is electrically connected to at least two of the second electrical contact points (37a-n) through electrical conductors connected to spaced-apart electrical contact points (39a, b, 47a, b) of the first electrode (5a, b, 6a-d; 38a, b, 42).

8. The apparatus according to claim 6 or 7, wherein the pre-resistor forming body (33) includes a sheet in which mutually separated current paths (36a to n) are formed, and the current paths (36a to n) of different electrical resistances differ in at least one of the length and the cross-sectional area perpendicular to the direction of progression of the current paths (36a to n) along the length of the current paths (36a to n).

9. The apparatus according to claim 8, wherein the pre-resistor forming body (33) is interposed between two of the first electrodes (5a, b, 6a-d; 38a, b, 42) in the array (26).

10. The apparatus according to any one of claims 1 to 9, wherein the first electrodes (5a, b, 6a-d; 38a, b, 42; 56a, b, 57a-f; 78a, b) are provided in the form of liquid-permeable sheets.

11. The apparatus according to claim 10, wherein at least two adjacent first electrodes (5a, b, 6a-d; 38a, b, 42; 56a, b, 57a-f; 78a, b) are separated from each other by at least one spacer (41a-d; 43a-c; 88a-g; 89a, b; 90a, b).

12. The apparatus according to claim 10 or 11, wherein the sheet includes a mesh.

13. The spacer includes threads (43a to c) of a material having a lower electrical conductivity than the material from which the mesh is made. The apparatus according to claims 11 and 12, wherein the threads (43a-c) are passed through at least one of the meshes included in the adjacent first electrodes (5a, b, 6a-d; 38a, b, 42; 56a, b, 57a-f; 78a, b) in the form of a sequence (45a-c) of stitches (44a-e).

14. A method for performing an electrolytic process using an apparatus, for example, the apparatus described in any one of claims 1 to 13, wherein the apparatus is A container (2;53) having an interior (3;54) for containing at least one type of electrolyte; An array (26; 77) of first electrodes (5a, b, 6a-d; 38a, b, 42; 56a, b, 57a-f; 78a, b) spaced apart and placed inside the container (2; 53); At least one second electrode (7a, b; 58a, b; 79), wherein at least a portion of the surface of the at least one second electrode (7a, b; 58a, b; 79) is positioned such that at least a portion of its surface is exposed to at least a portion of the inside of the container (3; 54) for containing at least one of the at least one electrolytes. Includes, The array (26; 77) of the first electrodes (5a, b, 6a-d; 38a, b, 42; 56a, b, 57a-f; 78a, b) includes at least one end electrode (5a, b; 56a, b; 78a, b) spaced between one of the second electrodes (7a, b; 58a, b; 79) on the one hand and all of the other first electrodes (6a-d; 38a, b, 42; 57a-f) of the array (26; 77) on the other hand. In addition to the end electrodes (5a, b; 56a, b; 78a, b), the array (26; 77) of the first electrodes (5a, b, 6a-d; 38a, b, 42; 56a, b, 57a-f; 78a, b) includes at least one first electrode (6a-d; 38a, b, 42; 57a-f) other than the end electrodes (5a, b; 56a, b; 78a, b), The aforementioned method, The steps include: providing the container (2; 53) with at least one electrolyte; The steps include: establishing a potential difference between the main surface of the first electrode (5a, b, 6a-d; 38a, b, 42; 56a, b, 57a-f; 78a, b) on the one hand and the second electrode (7a, b; 58a, b; 79) on the other hand, such that the first electrode (5a, b, 6a-d; 38a, b, 42; 56a, b, 57a-f; 78a, b) has polarity opposite to that of the second electrode (7a, b; 58a, b; 79), thereby causing a current to flow through the second electrode (7a, b; 58a, b; 79) and the main surface of the first electrode (5a, b, 6a-d; 38a, b, 42; 56a, b, 57a-f; 78a, b) on the other hand, such that the first electrode (5a, b;; 42; 56a, b; 57a-f; 78a, b) has polarity opposite to that of the second electrode (7a, b; 58a, b; 79); and In a method including, A method characterized in that the step of causing current to flow includes establishing a potential at least on the main surface of the end electrodes (5a, b; 56a, b; 78a, b) that is different from the potential at the main surface of the first electrodes (6a-d; 38a, b, 42; 57a-f) in the array (26; 77) other than the end electrodes (5a, b; 56a, b; 78a, b), by making it close to the potential of each of the second electrodes (7a, b; 58a, b; 79).

15. The method according to claim 14, wherein an ion in at least one of the aforementioned at least one electrolyte, for example, an ion containing a manganese species, is electrolytically oxidized, for example, as a step in a process of at least partially regenerating the etching solution.

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