ES2952138A1 - Electrowinning installation with interconnectable intercell bars (Machine-translation by Google Translate, not legally binding) - Google Patents

Abstract

Electrowinning installation with interconnectable intercell bars, of those used in electrodeposition installations, with at least three cells connected to each other in series by a set of two or three bars, a main central one, and one or two lateral ones placed between every two consecutive cells, the main bar giving support and electrical connection to one of the ends of all the cathode hangers of the previous cell and one of the ends of all the anode hangers of the next cell, and having switches electrical devices capable of establishing an electrical bridge between said bars periodically, for a short period of time, causing a temporary reversal of current. (Machine-translation by Google Translate, not legally binding)

Description

DESCRIPTION

Electrowinning installation with interconnectable intercell bars

This descriptive report refers, as its title indicates, to an electrowinning installation with interconnectable intercell bars, considering an electrowinning installation to be an electrodeposition installation used for the selective and pure recovery of the metals that are contained in a solution, which comprises at least three cells connected in a series circuit between the positive and negative poles of a rectifier, in which the electrical connection between each cell and the next is established by a set of at least two bars , a main bar, and one or two side bars placed between every two consecutive cells and parallel to each other a few centimeters.

The main bar acts in a conventional way and provides support and electrical connection to one of the ends of all the cathode hangers of the previous cell in the series of cells, where the first cell is the one connected to the positive pole of the rectifier, this bar The main cell also provides support and electrical connection to one of the ends of all the anode hangers of the next cell. One of the two side bars mentioned, the upper side bar, if it exists, provides support and connection to all the anodes of the previous cell, and the other bar, the lower side bar, if it exists, gives support and connection to all the cathodes of the next cell.

A few high current electrical switches installed uniformly along these bars provide them with the attribute of connectable bars, being able to establish an electrical bridge or connection between said bars, said connection being made periodically for a short period of time, causing the desired temporary reversal of current in the electrodes of a cell, then we will say that the cell is in a state of reversal. For a period tens of times longer, the switches remain open or without establishing the connection, during this period of open switches the cell is in its conventional production state.

field of invention

The invention relates to the field of metal electrodeposition plants and processes, especially electrowinning, in which the production cells containing the Electrodes and electrolyte are connected or can be connected to each other by an inter-cell electrical bar.

Current state of the art

For more than a hundred years, metal electrodeposition processes, especially electrowinning, have been widely used industrially. When they are used to create thin layers of coating, they are also often called “coatings” or “plating”.

The conventional electrical installation or connection for electro-deposition of metals, as illustrated in Figures 1 and 2, consists of a group of cells connected in series, in which we highlight the main elements:

- the positive pole of the rectifier that powers the series circuit of cells,

- the negative pole of the rectifier that powers the series circuit of cells,

- the anode hanger bars, below is the anode electrode plate,

- the cathode hanger bars, below is the cathode electrode plate,

- the conventional inter-cell bar, and

- the liquid electrolyte occupying the space between the anodes and the cathodes.

The metal deposited on the cathode is obtained by circulating a direct current between the anode and the cathode. On an industrial scale, in a production plant, this means tens of thousands of amperes applied to thousands of electrodes. The continuous circulation of these amperes for hours (ampere x hours) causes the deposition of the millions of tons of metal produced annually in these plants.

These electrowinning processes can produce very high quality metals with very high purity and fineness. However, since their origins a century ago, they intrinsically present serious technical difficulties with natural limitations that make their operation significantly more expensive and complicated, in addition to also making these processes more polluting.

The current density and, consequently, the density and manufacturing capacity have very strict technical limits, above which quality is lost, pollution increases and energy costs skyrocket. Furthermore, the electrochemistry of the process is very vulnerable to small and unavoidable deviations in the composition of minerals and process variables.

It has been more than a hundred years since the construction of the first industrial plants using conventional intercell bars, called "Walker bars", with their different versions or profiles. In this time, intense research and work has been carried out trying to mitigate and overcome the difficulties and technical problems noted.

Short circuits or direct anode-cathode contacts.

Accidental short circuits may occur due to placement error, non-parallel alignment of the electrodes, or physical deformation of the electrodes. It is evident that an improvement in the discipline of the work involved in their placement and in the quality of the plates that form them can and does resolve this accidental difficulty.

But, in addition to this, during the metal deposition process, protuberances appear, naturally and unpredictably, in the flat layer of metal generated, on the cathode plate, which usually has a surface area of approximately one square meter. These irregularities quickly grow in the form of dendrites and can easily come into contact with the anode located just about five centimeters from the cathode. These contacts cause short circuits with high currents, very destructive, which reduce production, destroy the physical integrity of the electrodes, contaminating the electrolyte and thus the metal produced, and at the end of the chain the environment.

An early solution to this important problem is to detect the overcurrent as early as possible and manually remove the short-circuit contact. Since it involves thousands and thousands of electrodes, and in a very hostile and dangerous environment, it has the disadvantage that it is a high-cost and low-efficiency task.

Another palliative procedure consists of the application of additives that refine the granulation of the deposited metallic crystal and make the creation of dendrites less likely, but these additives are somewhat polluting, high cost and relatively effective.

More sophisticated solutions are known, such as the application of segmented titanium anodes such as those described in patent WO2015/079072 “Anode structure for metal electrowinning cells”, but they have the disadvantage that they have a high cost as they require a coating composed of scarce materials given their high demand, such as ruthenium, iridium or rhodium. These anodes automatically disconnect the partial section in which the short-circuit contact is established, thus avoiding high currents, although as a result of the disconnection of the anode segment, a small obligatory collateral problem inevitably appears consisting of the copperization of the disconnected anode segment, due to which that said segment is covered with a layer of copper although it dissolves naturally once the dendrite is removed. This being a lesser evil, this solution should be operational, however its real implementation and industrial validation suffers from unexpected difficulties.

Quality and capacity

The electrode plates work efficiently at very low current densities, of the order of about 300 Amperes per m2, that is, 30 mA per cm2, considered in comparison with a copper conductor of a few millimeters that can carry tens of thousands of mA. As a consequence, this forces us to work in very large plants with high construction and operating costs. Exceeding current density limits for the sake of greater productivity or productive concentration means paying the price of poorer metal quality, a drastic increase in dendrite short circuits such as those described above, a loss of performance and greater contamination.

It is surprising and very interesting to know that for decades there have been clear and conclusive studies that show and propose a recognized technical solution to all the natural difficulties noted in these electrochemical processes, eliminating the root of the underlying intrinsic limitation suffered by these electrochemical processes. -deposition, as for example described in patent US4140596 “Princess for the electrolytic refining of copper'. This solution consists of the periodic inversion of the electric current in electrodes, as proposed in the patent, for 0.355 seconds, for the following 7.1 seconds to work directly productively. This would apparently mean reversing or cyclically undoing 5 percent of what was previously manufactured, but reality proves, and theories justify, that on the contrary, this short reversal of current cleanses the barriers of electrochemical potentials that become caked and are the source of all the natural difficulties noted above for these processes.

There are works already consolidated and accepted by the scientific community that explain this phenomenon through the study of the ionic layers that originate on the surface of the electrodes or in their proximity, and the effectiveness of periodic current reversal, or what is the same, the application of periodically repeated current pulses and/or reverse pulses. Thus appears the concept of the existence of a capacitive ionic layer, the Helmholtz layer, whose creation would be the root of the severe limitations of these processes described above.

The theoretical procedure of applying a current in the opposite direction to the production current periodically seems to be the solution, but the real technical problem is the serious difficulty of how to make it a reality or how to implement it practically and operationally on a large scale in a real industrial production plant. . In a laboratory with cathode plates measuring a few square centimeters operating under a few amperes, it is easy to implement an electrical installation that allows us to experiment, find and apply a highly satisfactory solution. However, in an industrial plant, a few square centimeters become thousands and thousands of square meters of electrode surface, and a few amperes become tens of thousands of amperes.

The sudden and periodic change of direction of these high currents of tens of thousands of amperes has been attempted to be obtained by superimposing or adding another alternating addition to the conventional direct current, the standard being an alternating wave with a sinusoidal temporal profile that reaches our homes. and it is also used in the industry, which in its negative peak exceeds the amplitude of the always positive direct current, giving rise to the sum of both having a long period of positive values against a moment of reverse current, as described in the patents WO2015056121 “Metal-electmwinning or -electrorefining process comprising the application of an electrical power signal formed of an alternating current superimposed on a direct current' and WO2015075634 “Method of superimposing alternating current on direct current for methods for the electrowinning or electrorefining of copper or other products, in which the alternating current source is connected between two consecutive cells of the electrolytic cell group using an inductor for injecting alternating current and a capacitor for closing the electric circuit". The problem with these solutions is the extreme magnitude of the electrical devices necessary for the coupling of both alternating and direct powers, with large capacitors and gigantic coils operating at thousands of hertz, and the technical difficulties they entail, which make their practical execution real. is currently unrealizable on an industrial level. These solutions also require a contribution of external supplementary energy in alternating current.

Another solution is also known, as described in patent P201930869 “Electrodeposition installation with active intercell bars”, corresponding to a SAIB or BIAI type installation that also uses periodic current inversion, and that, like our current invention , makes use of its own internal energy stored in the production process. It does this by dividing or distributing the magnitude of the problem into millions of micro switching devices inserted in the intercell bars of the plant, in each of them we work with amplitudes affordable for today's modern transistors. This is a viable solution although it presents the drawback of construction complexity, given the extreme number of production switching devices that have to be integrated inside the copper of the intercell connection bars, which requires complex manufacturing of these bars. and complicates its maintenance and/or repair.

Description of the invention

To solve the current problem caused by the intrinsic background limitation of these industrial processes, short circuits due to dendrites and performance losses in metal electro-deposition installations, the electro-winning installation with interconnectable intercell bars has been devised. object of the present invention, which comprises

- at least three cells connected in series between the positive and negative poles of a rectifier, each cell comprising a plurality of anodes and cathodes supported on their respective hangers, the first cell being the one connected to the positive of the rectifier,

- a set of at least two electrical connection bars arranged in parallel between each cell and the next, being a main bar and at least one side bar, which may be an upper side bar, a lower side bar, or both, and being placed at a sufficient distance so that there is no risk of electrical contact, normally a few centimeters at normal working voltages,

- a plurality of high current electrical switches, remotely activatable and deactivatable by means of communication, electrically connected between the main bus and the side bus or bars and distributed uniformly along the electrical connection bars, and

- at least one control device equipped with means of communication with the electrical switches, preferably being a computer and/or electronic device configurable, responsible for giving periodic orders for activation/deactivation of electrical switches,

- each main bar being mechanical support and electrical connection of one of the ends of all the cathode hangers of the previous cell in the series of cells, and also being mechanical support and electrical connection of one of the ends of all the cathode hangers. the anodes of the next cell,

- each upper side bar, if existing, being mechanical support and electrical connection of all the anodes of the previous cell, and

- each lower side bar, if present, being mechanical support and electrical connection of all the cathodes of the following cell.

We refer generically to at least three cells, the first cell, any intermediate cell and the last cell, to represent in the simplest way a conventional industrial plant composed of hundreds of cells and explain the invention applied to it. This requirement is not exclusive for the operation of our invention, since a single cell, or two cells, could also be directly benefited by our invention, although it does not represent a real industrial installation.

Electrical switches can be either solid-state electronic switches or electromechanical power switches or relays, or any combination of both. They can be associated with a printed circuit board equipped with a microcontroller with the capacity to communicate using digital communication protocols with the control equipment, and optionally also incorporate current sensors.

High current electrical switches allow electrical connections to be established selectively between the bars associated with a cell. These connections are activated and deactivated periodically, establishing for a short period of time an electrical contact between some of the bars adjacent to a cell, which causes a temporary reversal of current in the electrodes of said cell with natural discharge of the Helmholtz ionic layer without the need for external energy input, and, for a period tens of times longer, the contacts of the electrical switches remain open. For example, one second of contact or connection and twenty seconds open without connection.

The activation of the reversing switches must be applied periodically to each of the cells in the cell series circuit. Closing the switches of all the cells at the same time would cause a short circuit collapse in the general rectifier. If we let it be the chance of non-synchronized clocks, or we let the different controllers of the different cells be the ones that randomly trigger the connection or reversal instant, we will obtain a statistical distribution in the form of the well-known binomial distribution that would result in a naturally occurring homogeneous for large numbers. But we would face infrequent but certain coincidences of simultaneous reversals that could produce some small instability in the general rectifier.

As a consequence of the previous lines, an orderly and simple deterministic action is proposed for the current inversion procedure in the cells of the circuit.

We act in an orderly manner using an index "i" which is the cell number to which we apply the short inversion period, that is, with activated switches, so that when cell one finishes its inversion state it is started by cell two. , and so on ( i = i 1 ), one at a time. Once the investment has reached the last cell it would start again.

If the number of cells is large, which is the most common case in an industrial installation, it is clear that it may happen that we need to invert cell one again before reaching the last cell. We must establish some parameters to analyze the problem and its solution:

- E1 is the state in which the electrical switches of a cell are activated, and therefore in electrical conduction. It corresponds to the electrodes in inversion.

- T1 is the configurable time in the control equipment in which the electrical switches are in state E1 in each cycle,

- E0 is the state in which the electrical switches of a cell are deactivated, and therefore without electrical conduction. Corresponds to the electrodes in production. - T0 is the configurable time in the control equipment in which the electrical switches are in state E0 in each cycle, and

- NC is the number of cells that make up the series circuit between the positive and negative poles,

The sweep time of the inversion wave of the NC cells of the circuit, concatenating the connection of the electrical switches of the cells successively, is NC x T1 following the explained sequence.

The time it takes for cell one to request its second or next investment is T0 T1.

As we have said, the problem, in case the number of cells is large, appears when NC x T1 > T0 T1, then state E1 needs to be reached in more than one cell at a time.

When NC x T1 = T0 T1, just at the end of E1 in cell NC (last cell), cell one will enter E1. If NC is cleared, and now using NCP as the number of cells per packet, we have the formula NCP = (T0 T1) / T1, always adjusting decimals of T0 and T1 so that it is an integer.

The number of cell packs in which the cycle must be performed will be NP = NC / NCP

If the number of cell packets is called p, each packet p will be composed of cells (p-1) x NCP i, where i goes from i=1 to i =NCP. If NP is not an integer, it is rounded up: NP = truncate (NP)+1.

Thus, in general, the cell sweep in inversion E1 will be:

Cell number in E1 inversion = (p-1) x NCP i,

where i goes from i = 1 to i = NCP, and p goes from p = 1 to p = NP. In this way, at all times there are NP cells with closed switches, stably, avoiding fluctuations in the rectifier supply.

Applying the formulation to the example proposed above with the times of T0 = 7.1 sec. and T1 = 0.355 sec. we obtain NCP = (7.1 0.355) / 0.355 = 21.

In a case of a circuit of, for example, 63 cells, then NP = 63 / 21 = 3. 3 packages of 21 cells each are considered. The same sequence procedure will be applied to each package:

Package 1, with circuit cells 1,2,3...21

Package 2, with circuit cells 22,23,24.42

Package 3, with circuit cells 43,44,45.63

When i=1 and p=1 cell 1 is inverted

When i=1 and p=2, cell 22 is inverted

When i=1 and p=3, cell 43 is inverted

When i=2 and p=1 cell 2 is inverted

When i=2 and p=2 cell 23 is inverted

When i=2 and p=1 cell 44 is inverted

When i=21 and p=3 cell 63 is inverted

Following this sequence, there would be 3 cells at a time with the switches closed making the inversion, but never consecutively, with which the process would be carried out in a stable manner, avoiding fluctuations.

To explain the interconnection between the bars that causes the reversal of currents in the electrodes of a cell, we will first name the bars to refer to them.

- Each cell is preceded (according to the direction of advance of the electric current, from the positive pole to the negative pole, in the series circuit of cells) by a trio of bars that we will call previous bars: a main anterior bar and two lateral anterior bars. which are the previous top sidebar and the previous bottom sidebar.

- Each cell is followed (according to the direction of the electric current, from the positive pole to the negative pole, in the series circuit of cells) by a trio of bars that we will call rear bars: a main rear bar and two front side bars. which are the upper back sidebar and the lower back sidebar.

In this electrowinning installation, the reversing electrical switches of the electrodes of a cell are placed between the front main bar and the front lower side bar, if present, and between the rear main bar and the rear upper side bar, if present. if it exists. Versions with two and three bars are planned. These switches will activate and deactivate in unison in each cell causing the current to reverse in the cell's electrodes.

The characteristic operating procedure is the following, which is carried out simultaneously in each cell pack, in case there are several cell packs:

- being the number of cells per NCP packet = (T0 T1) / T1,

- being i the cell index in each packet, which will start with i=1,

The following sequence is carried out:

- in a first step, the electrical switches of cell i are set to state E1 (closed), keeping the electrical switches of all the other cells of the package in state E0 (open),

- in a second step, time T1 is allowed to elapse,

- in a third step, the electrical switches of cell i of the package are set to state E0a,

- the value of i is increased by 1 (i =i+1) and the previous steps are repeated sequentially for the following cells, from 1 to NCP, simultaneously in each packet, if there are several.

Thus, when i=1 we put the first cell of all the packets in E1, when i=2 we put the second cell of all the packets in E1,... when i = NCP we put the last cell of all the packets in E1.

Obviously, if the number of cells were not high, only one cell pack would be considered to exist.

Advantages of the invention

The great value of this invention consists of the substantial improvements in quality and productivity that its application causes in the annual production of millions of tons of metals, such as copper, nickel, zinc inc., together with the simplicity and robustness of the mechanism that supports it, which makes it immediately industrially applicable.

This installation of intercell bars with current inversion that is presented applies the periodic inversion of currents through an arrangement of high current electronic switches that provides multiple advantages over the systems currently available, the most important being that it improves the current state of the art. , especially electro-deposition installations with active intercell bars that require millions of micro switching devices inserted into the intercell bars of the plant, one for each segment.

Unlike solutions known in the state of the art that require an external supplementary energy input in alternating current, the invention presented has the great advantage that it makes use of its own switching strategy that makes use of the stored natural energy itself. in the electrowinning process for the generation of a reverse current and elimination or discharge of the harmful Helmholtz ionic layer, through the high current switch plates acting between the triple of bars in a convenient way.

Among these improvements we must highlight greater robustness of operation and safety, since the main transistors or switches required, in an enormous quantity, by electro-deposition installations with known active intercell bars, intercept the passage of the total production current, Therefore, its potential breakage or breakdown affects production until its repair or replacement, operations that are very complicated and delicate given that these switches are embedded inside the intercell bar. This is solved in the invention presented since the electrical switches act in parallel with the main current, and they do so only for the short period of time that the inversion lasts, so in case of breakage, it does not affect the production current. .

Another advantage is that, when operating the electrical switches in parallel, the neighboring switching devices, suitably oversized, provide sufficient reverse current for effective operational continuity, thus the system is fault tolerant, in terms of subsequent replacement as they are not embedded. on the intercell bar, but simply coupled and installed on it, making this operation much more viable and easier to perform.

It is also important to highlight that, since the electrical switches do not have to support the plant load through them, and only provide or superimpose the inversion current for a short period, they are significantly reduced in number and also in their ease of operation. installation, reducing both the economic cost of the installation, which is reduced by almost half, and the probability of failures and breakdowns.

Another notable advantage obtained is that the control system is much simpler and more general, as it does not necessarily require wireless and low power activity in its control activity, since, given its simplicity and the smaller number of switches required, it is wiring through the bar itself is possible, using the plastic support channel of the secondary intercell bars, thus avoiding the consumption of thousands and thousands of batteries and the difficult management of such a complex synchronized control through a radio network required in the electro-deposition installations with active intercell bars known so far.

Finally, we must highlight the ease of initial installation and start-up, unlike electro-deposition installations with active intercell bars known to date, which allows even subsequent maintenance to be in the hands of the client themselves. of a company with low control specialization, as required in facilities in the mining environment.

Description of the figures

To better understand the object of the present invention, a conventional installation has been represented in the attached plan, and two practical embodiments of an electrowinning installation with interconnectable intercell bars. In the figures where applicable, the symbol of an arrow with an open head ( > ) has been used to represent the production currents, and an arrow with a closed head ( ►) to represent the reverse currents that can be obtained with this invention.

In said plane, figure -1- shows a representative section of a conventional electro-deposition installation for electro-winning that consists of three portions of three cells.

Figure -2- shows a representative section of a conventional electrodeposition installation including the direction of the production currents through the hanger bars and through the electrolyte in its normal operation.

Figure -3- shows a representative section of an electro-deposition installation, in an embodiment with three intercell bars, with the electrical switches open, not activated.

Figure -4- shows a representative section of an electro-deposition installation, in an embodiment with three intercell bars, including the direction of the currents in its normal or production operation, with the electrical switches being open, not activated.

Figure -5- shows a representative section of an electro-deposition installation, in an embodiment with three intercell bars, in which the electrical switches of the central cell of the bar system have been closed, allowing reverse currents to be generated. The electrical switches corresponding to the central cell are closed, that is, activated.

Figure -6- shows a representative section of an electro-deposition installation, in an embodiment with two intercell bars with a lower side bar, including the direction of the currents in its normal or production operation, with the electrical switches open, not activated.

Figure -7- shows a representative section of an electro-deposition installation, in an embodiment with two intercell bars with an upper side bar, including the direction of the currents in its normal or production operation, with the electrical switches open, not activated.

Figure -8- shows a representative section of an electro-deposition installation, in an embodiment with two intercell bars with a lower side bar in which the electrical switches of the central cell of the bar system have been closed, allowing reverse currents to be generated. . The electrical switches corresponding to the central cell are closed, that is, activated.

Figure -9- shows a representative section of an electro-deposition installation, in an embodiment with three intercell bars, but in which only two of them are used, the main one and the upper one, to generate the reverse current, in the that the electrical switches of the central cell of the bus system have been closed, allowing the generation of the reverse currents. The electrical switches corresponding to the central cell are closed, that is, activated.

Figure -10- represents in a simplified manner the control equipment connected through the corresponding communication means with the electrical switches of the cells, in an embodiment with three intercell bars.

Figure -11- represents in a simplified manner the control equipment connected through the corresponding communication means with the electrical switches of the cells, in an embodiment with two intercell bars, with a lower side bar.

Figure -12- represents in a simplified manner the control equipment connected through the corresponding communication means with the electrical switches of the cells, in an embodiment with two intercell bars, with an upper side bar.

Preferred embodiment of the invention

The constitution and characteristics of the invention can be better understood with the following description made with reference to the attached figures.

To understand the invention, it is convenient to take into account the configuration of representative elements of a conventional electro-deposition installation, which is the same for electro-winning or electro-refining of metals, which is illustrated in Figures 1 and 2. In it We can see the main elements of a conventional installation:

- the positive pole (10) of the rectifier that powers the series circuit of cells,

- the negative pole (11) of the rectifier that powers the series circuit of cells, - the anode hanger bars (3), below is the anode electrode plate, - the cathode hanger bars (2), below is the plate cathode electrode, - the conventional inter-cell bar (8),

and the area surrounding and between the anodes (3) and the cathodes (2) representing the liquid electrolyte.

Figure 2 represents the direction of the productive currents through the hanger bars and through the electrolyte in normal operation.

As can be seen in Figures 3, 4, 5, 6, 7, 8, 9 and 10, an electrowinning installation with interconnectable intercell bars with current inversion is illustrated as the object of this invention comprising

- at least three cells connected in series between the positive (10) and negative (11) poles of a rectifier, each cell comprising a plurality of anodes (3) and cathodes (2) supported on their respective hangers, the first cell being the one connected to the positive of the rectifier,

- a set of at least two electrical connection bars arranged in parallel between each cell and the next, being a main bar (1) and at least one side bar, which may be an upper side bar (4), a lower side bar (5), or both, being placed at a sufficient distance so that there is no risk of electrical contact, normally a few centimeters at the usual working voltages,

- a plurality of high current electrical switches (7), remotely activated and deactivated by means of communication, electrically connected between the main bar (1) and the side bar or bars (4, 5) and distributed uniformly along the electrical connection bars (1, 4, 5), and - at least one control equipment (13) provided with means of communication with the electrical switches (7),

- each main bar (1) being mechanical support and electrical connection of one of the ends of all the cathode hangers (2) of the previous cell in the series of cells and also being mechanical support and electrical connection of one of the ends of all the anode hangers (3) of the next cell,

- each upper side bar (4), if present, being mechanical support and electrical connection of all the anodes (3) of the previous cell, and

- each lower side bar (5), if present, being mechanical support and electrical connection of all the cathodes (2) of the following cell.

To facilitate understanding of how it works, we will take the convention that:

- each cell is preceded in the series circuit of cells, according to the direction of advance of the electric current, from the positive pole to the negative pole, by bars, two or three, which we will call previous bars: a main bar (1) previous , the bar upper anterior lateral bar (4), if applicable, and the lower anterior lateral bar (4), if applicable.

- each cell is followed in the series circuit of cells, according to the direction of advance of the electric current, from the positive pole to the negative pole, by bars, two or three, which we will call rear bars: a rear main bar (1) , the upper rear side bar (4), if applicable, and the lower rear side bar (4), if applicable.

In this electrowinning installation, in a preferred embodiment with three bars, as illustrated in Figures 3, 4 and 5, the electrical switches (7) associated with each cell are electrically connected between the main bar (1) above and the lower anterior side bar (5) and between the main rear bar (1) and the upper rear side bar (4). These electrical switches (7) establish electrical bridges between the main bar (1) and the two side bars (4, 5) associated with a cell, causing current inversion in the cell's electrodes. In figure 4 we see the electrical switches (7) open and in figure 5 we see the electrical switches (7) closed in the central cell.

An alternative embodiment of the simpler electrowinning installation is possible, with only two bars, as illustrated in Figures 6, 7 and 8, in which the electrical switches (7) associated with each cell are electrically connected between the front main bar (1) and the front side bars (5), as illustrated in Figures 6 and 8, or between the rear main bars (1) and the rear upper side bars (4), as illustrated in the Figure 7, It is also possible to use three intercell bars, but only use the electrical switches (7) between the main bars (1) and one of the side bars (4, 5), as illustrated in Figure 9. These electrical switches (7) establish electrical bridges between the main bar (1) and the side bars (4, 5) associated with a cell, causing current inversion in the cell electrodes. In figures 4, 6 and 7 we see the electrical switches (7) open and in figures 5, 8 and 9 we see the electrical switches (7) closed in the central cell.

In an electrowinning installation, the existing side bars (4.5) will preferably have a section of at least 200 mm2, while the main bar (1) may be the one that is usually used in the plant, which is usually between 575 mm2 and 1280 mm2, depending on whether it uses bars with more complicated profiles. In an electrowinning installation, the amplitude of the reverse currents (12) that is generated, although of short duration, are very intense, on the order of 2.5 times the production current. To do this, 32 electrical switches (7) will preferably be installed per cell, 16 on each side of the cell, oversizing these electrical switches (7) for robustness so that they preferably have a pass resistance between 2.5 and 5 micro ohms.

The means of communication between the control equipment (13) and the electrical switches (7) are preferably chosen from the group consisting of wired or wireless.

The electrical switches (7) can be either solid state electronic switches or electromechanical power switches or relays, or any combination of both. It is planned that, in an alternative embodiment, the electrical switches (7) are associated with a printed circuit board equipped with a microcontroller with the capacity to communicate using digital communication protocols with the control equipment (13). Optionally, the printed circuit boards associated with the electrical switches (7) will also have current sensors.

The high current electrical switches (7) allow electrical connections to be established selectively between the bars (1, 4, 5). These connections are activated and deactivated periodically, establishing an electrical contact between said bars for a short period of time, which causes a temporary reversal of current with natural discharge of the Helmholtz ionic layer without the need for external energy input, and, for a period of time, period tens of times longer, the contacts of the electrical switches (7) remain open.

This installation involves a characteristic current reversal procedure, for reasons of stability of the general power supply to the series circuit of cells, in which,

- E1 is the state in which the electrical switches (7) associated with a cell are activated, and therefore in electrical conduction. It corresponds to the electrodes in inversion.

- T1 is the configurable time in the control equipment in which the electrical switches are in state E1 in each cycle,

- E0 is the state in which the electrical switches (7) associated with a cell are deactivated, and therefore without electrical conduction. Corresponds to the electrodes in production.

- T0 is the configurable time in the control equipment in which the electrical switches (7) are in state E0 in each cycle, and

- NC is the number of cells that make up the series circuit between the positive and negative poles,

- NCP is the number of cells per packet, calculated as NCP = (T0 T1) / T1, always adjusting decimals of T0 and T1 so that it is an integer,

- i is the cell index in each packet, which will start with i=1,

The following sequence is carried out simultaneously in each of the cell packs:

- in a first step, the electrical switches (7) associated with cell i are placed in state E1 (closed), keeping the electrical switches associated with all the other cells of the package in state E0 (open),

- in a second step, time T1 is allowed to elapse,

- in a third step, the electrical switches (7) associated with cell i of the package are set to state E0,

- the value of i is increased by 1 (i =i+1) and the previous steps are repeated sequentially for the following cells, from 1 to NCP, simultaneously in each packet, if there are several.

Thus, when i=1 we put the first cell of all the packets in E1, when i=2 we put the second cell of all the packets in E1,... when i = NCP we put the last cell of all the packets in E1.

Obviously, if the number of cells were not high, only one cell pack would be considered to exist.

The objective that we pursue and achieve is the periodic reversal of the current in each and every one of the electrodes of a cell, through the appropriate design of the aforementioned bars and the proposed switches that make up the invention. This has been confirmed experimentally in our laboratory:

In this electrowinning installation, by activating the switches (7) to the bars (1) and (4) and (5), through these and through the hanging bars, we are applying the electrical bridge to each of the electrodes or pairs of electrodes anode (3) cathode (2). For example, using 8 8 = 16 switches per cell would be an acceptable compromise between simplification by grouping and traveling on the reverse current transport bars and the switches. The path of the discharge or reverse currents (12) must be limited given that in a single cell working at 600 A/2, with electrodes over a square meter and 63 cathodes, applying a double amplitude of reverse current compared to the direct, discharge 63+1200 = 75600 amperes which, if they were to travel many meters along the bar longitudinally, would require a large section in said bar, which in practice is not achievable or reasonably available.

It may be surprising that the sole action of establishing an electrical bridge between an anode (3) and cathode (2) pair produces a desired reverse current (12) of significant magnitude, more than 600 A/2. We include the discovery of this fact obtained experimentally to explain that the current is generated by the energy stored in the plates and that it is presented as a voltage generated by a battery.

The replication carried out experimentally in the laboratory of the invention on a small scale and the performance of dozens of tests confirm the most optimistic reports on the immediate benefit of periodic current reversal when executed with the described switching design, as shown in Figures 4 and 5. The quality of the deposited copper is, at high densities, double or triple the nominal with the described procedure, or pulsing, equal to or better than the copper deposited at low currents without pulsing.

The replication of the invention on a small scale in our laboratory and the performance of dozens of tests confirm the most optimistic estimates about the immediate benefit of periodic current reversal operating with the switching design described above. The resistance of the micro cell operating at low load, at about 200 A/2, is of the order of 0.96 mOHM per m2. If the current density is increased to 900 N m2, 4.5 times more, but applying the described procedure of periodic current inversion, which we will also call pulsing, with the invention, the passivation or polarization of the anode (3) does not appear, therefore On the contrary, the resistance of our micro cell drops to 0.77 mOHM per m2. The copper plate produced at this high current density for about 14 hours with pulsing has a perfectly acceptable grain. The Application in the same cell and conditions of 900 A/2 without pulsing triggers in a few hours an anode (3) cathode (2) resistance of about 1.85 mOHM per m2, an increase that shows the inevitable passivation of the anode (3). .

The person skilled in the art will readily understand that he can combine features of different embodiments with features of other possible embodiments, provided that such combination is technically possible.

All information referring to examples or embodiments forms part of the description of the invention.

Claims (1)

1 - Electrowinning installation with interconnectable intercell bars, characterized in that it includes - at least three cells connected in series between the positive (10) and negative (11) poles of a rectifier, each cell comprising a plurality of anodes (3) and cathodes (2) supported on their respective hangers, the first cell being the one connected to the positive of the rectifier, - a set of at least two electrical connection bars arranged in parallel between each cell and the next, being a main bar (1) and at least one side bar, which may be an upper side bar (4), a lower side bar (5), or both, - a plurality of high current electrical switches (7), remotely activated and deactivated by means of communication, electrically connected between the main bar (1) and the side bar or bars (4, 5) and distributed uniformly along the electrical connection bars (1, 4, 5), and - at least one control equipment (13) provided with means of communication with the electrical switches (7), - each main bar (1) being mechanical support and electrical connection of one of the ends of all the cathode hangers (2) of the previous cell in the series of cells and also being mechanical support and electrical connection of one of the ends of all the anode hangers (3) of the next cell. - each upper side bar (4), if existing, being mechanical support and electrical connection of all the anodes (3) of the previous cell, and - each lower side bar (5), if any, is the mechanical support and electrical connection of all the cathodes (2) of the next cell.2 2 - Electrowinning installation with interconnectable intercell bars, according to the previous claim, characterized in that it comprises a main bar (1) and an upper side bar (4) located on the main bar (1). 3 - Electrowinning installation with interconnectable intercell bars, according to any of the previous claims, characterized in that it comprises a main bar (1) and a lower side bar (5) located under the main bar (1). 4 - Electrowinning installation with interconnectable intercell bars, according to any of the previous claims, characterized in that it comprises a main bar (1), an upper side bar (4) and a lower side bar (5), in this case being the main bar (1) located between the top sidebar (4) and the bottom sidebar (5). 5 - Electrowinning installation with interconnectable intercell bars, according to any of the previous claims, characterized in that the means of communication between the control equipment (13) and the electrical switches (7) are chosen from the group formed by wired or wireless. 6 - Electrowinning installation with interconnectable intercell bars, according to any of the previous claims, characterized in that the electrical switches (7) are associated with a printed circuit board equipped with a microcontroller with the capacity to communicate using digital communication protocols with the equipment. control (13). 7 - Electrowinning installation with interconnectable intercell bars, according to any of the previous claims, characterized in that the printed circuit boards associated with the electrical switches (7) have current sensors. 8 - Electrowinning installation with interconnectable intercell bars, according to any of the previous claims, characterized in that the first cell connected directly to the positive pole (10), and the last cell connected directly to the negative pole (11), are semi-circular cells. -sacrifice without current reversal. 9 - Electrowinning installation with interconnectable intercell bars, according to any of claims 1 to 7, characterized in that the first cell connected directly to the positive pole (10), and the last cell connected directly to the negative pole (11), are power resistors, with a resistive value similar to that of the cells. 10 - Current inversion procedure of an electrowinning installation with interconnectable intercell bars, according to any of the previous claims, characterized in that - E1 being the state in which the electrical switches (7) associated with a cell are activated, and therefore in electrical conduction, - T1 being the configurable time in the control equipment in which the electrical switches are in state E1 in each cycle, - E0 being the state in which the electrical switches (7) associated with a cell are deactivated, and therefore without electrical conduction, - T0 being the configurable time in the control equipment in which the electrical switches (7) are in state E0 in each cycle, - NC being the number of cells that make up the series circuit between the positive and negative poles, - NCP being the number of cells per packet, calculated as NCP = (T0 T1) / T1, always adjusting decimals of T0 and T1 so that it is an integer, and - being i the cell index in each packet, which will begin with i=1, The following sequence is carried out simultaneously in each of the cell packs: - in a first step, the electrical switches (7) associated with cell i are placed in state E1 (closed), keeping the electrical switches associated with all the other cells of the package in state E0 (open), - in a second step, time T1 is allowed to elapse, - in a third step, the electrical switches (7) associated with cell i of the package are set to state E0, - the value of i is increased by 1 (i =i+1) and the previous steps are repeated sequentially for the following cells, from 1 to NCP, simultaneously in each packet, if there are several.