HK1215457B - System for evaluation of current distribution in electrodes of electrochemical plants - Google Patents

Description

System for evaluating current distribution in electrodes of an electrochemical plant

Technical Field

The present invention relates to a method for directly detecting the current supplied to the electrodes of an electrolysis cell, in particular in plants for the electrolytic precipitation or electrolytic refining of non-ferrous metals.

Background Art

The current supplied to electrolytic cells used in electrochemical plants, particularly those used for metal electrodeposition (such as metal electrolytic precipitation or electrorefining), can be distributed in a highly variable manner among the various electrodes installed, negatively impacting production. This phenomenon can occur for several reasons. For example, in the particular case of metal electrolytic precipitation or electrorefining, the negative polarity electrodes (cathodes) are frequently removed from their bases to allow the product deposited thereon to be collected, and then subsequently replaced for the next production cycle. This frequent handling, often performed on a very large number of cathodes, often leads to imperfect repositioning on the associated busbars and less-than-ideal electrical contact, which can also be caused by dirt deposited in the receiving bases. Product deposition can also occur in an irregular manner on the electrodes, forming mass transport gradients that alter the cathode surface profile. When this occurs, an electrical imbalance is established because the anode-to-cathode gap is no longer constant across the entire electrode surface: the electrical resistance becomes variable as a function of the distance between each anode and cathode pair, exacerbating the problem of irregular current distribution.

Therefore, the current can be distributed to each electrode in different amounts, not only because of poor electrical contact between the electrode and the busbar, but also because of changes in the cathode surface profile. In addition, even simple wear of the anode can affect the current distribution.

These current distribution inhomogeneities can lead to anode-to-cathode short circuits. Another common cause of short circuits, particularly in the case of copper electrodeposition, is the accidental formation of dendritic deposits, which grow locally at a faster rate as soon as the local anode-to-cathode gap decreases, resulting in an increase in the portion of the current concentrated at the dendrite's growth point until a short circuit condition between cathode and anode begins to occur. In the event of a short circuit, the current tends to concentrate at the shorted cathode, reducing the current to the remaining cathodes and severely hindering production until the shorted cathode is disconnected, or recovery is impossible.

Besides generating a loss of quality and productivity, as indicated above, the uneven current distribution puts at risk the integrity of high-grade anodes obtained from titanium mesh, shortening their lifespan.

In a plant, the task of detecting irregularities in the current distribution is extremely complex, given the large number of cells and electrodes present. Indeed, such detection involves thousands of manual measurements performed by operators using infrared or magnetic detectors. In the particular case of metal electrolytic precipitation and electrorefining plants, these measurements are performed by operators in a high-temperature environment and in the presence of acid mists consisting primarily of sulfuric acid.

Furthermore, traditional manual elements used by the operator, such as gauss meters or instruments with infrared sensors, only allow locating large current distribution imbalances, since they actually detect imbalances associated with magnetic fields or temperature changes.

These manual or semi-manual systems have the disadvantages of being unsuitable for continuous operation (allowing only spot checks), being very expensive, and being potentially hazardous to the health of the operators.

Known systems for wireless monitoring of tanks, although permanent and continuously working, only detect voltage and temperature changes for each tank (and not for each single electrode). As explained above, this information is imprecise and generally insufficient.

An attempt to overcome the aforementioned problems is disclosed, for example, in WO2013037899. The invention described in this patent application has the disadvantage of requiring thousands of contacts to be attached directly to the busbar, a complex task to perform in the factory during operation. Furthermore, this indirect current measurement requires the use of complex calculation models that must accommodate several approximations.

For these reasons, the industry has expressed the need to have a technically and economically feasible system for permanently and continuously monitoring and measuring the current distribution in each of the electrodes installed in the cells of a metal electrodeposition plant.

Summary of the Invention

The present invention allows the current distribution of an almost unlimited number of electrodes installed in an electrochemical plant, such as a plant for the electrowinning of non-ferrous metals (e.g. electrolytic extraction or electrolytic precipitation and electrolytic refining or electrolytic refining), to be detected without requiring operator intervention to perform manual measurements in an unhealthy environment, and can signal the failure of one or more specific electrodes via an alarm system. The present invention also allows the calculation and installation complexity of the indirect measurement systems of the prior art to be overcome, as the system can be adapted for direct installation on the electrodes during their manufacturing phase.

Various aspects of the invention are set out in the accompanying claims.

In one aspect, the present invention relates to a system for evaluating current distribution in cathodes and anodes of a metal electrodeposition plant, the system comprising:

at least one electrolytic cell containing an electrolyte;

a current busbar associated with the at least one electrolytic cell;

a plurality of cathodes and anodes having cathode and anode hanger bars disposed thereon in electrical contact therewith, said cathode and anode hanger bars having uniform resistivity and regular geometry, said hanger bars having terminal members adjacent to said current bus bars and adapted to maintain the corresponding cathodes and anodes in position within said at least one electrolytic cell;

The cathode and anode hanger rods are equipped with at least one electrical probe, which is connected to at least two contact detection points located on the cathode and anode hanger rods in the area defined by the electrical connection to the current bus and the first electrical connection to the corresponding cathode or anode.

The term "first electrical connection" between the cathode and anode hanger bars and the electrodes connected thereto (cathode and anode, respectively) is used herein to refer to the first contact point to which electrical current arrives starting from its source side.

The inventors have found that when the geometry of the electrode hanger rod is regular, it is possible through the measurements of the present invention to infer the current distribution on the electrodes coupled to the electrode hanger rod.

Electrochemical metal deposition plants are known in the art in which the cells are configured to receive current from only one side, or are equipped with balanced secondary current busbars for current redistribution. In the latter case, the system of the invention is arranged so as to comprise:

at least one electrolytic cell containing an electrolyte;

a current busbar associated with the at least one electrolytic cell;

Balanced secondary busbar;

a plurality of cathodes and anodes having cathode and anode hanger bars positioned thereon in electrical contact therewith, the cathode and anode hanger bars having uniform resistivity and regular geometry, the hanger bars having first terminal members adjacent the current busbars and second terminal members adjacent the balancing secondary busbars, the hanger bars being adapted to maintain the corresponding cathodes and anodes in position within the at least one electrolytic cell;

The cathode and anode hanger rods are equipped with at least one electrical probe, which is connected to at least four contact detection points located on the cathode and anode hanger rods in the area defined by the electrical connections to the current bus and the balancing secondary bus respectively and the first electrical connection to the corresponding cathode or anode.

In one embodiment of the system according to the invention, said cathode and anode hanger bars are equipped with at least one microcircuit having a microprocessor connected thereto, said microcircuit being electrically connected to said contact detection points.

To avoid connecting the electrode hanger rod to multiple cables, a complex operation for plant managers, the ohmic voltage drop measurement can be transmitted via a radio transmitter to a central computer for necessary processing. For this reason, according to a further embodiment of the system according to the invention, the microprocessor microcircuit is also equipped with a radio transmitter. In some cases, the resistivity of the electrode hanger rod can be affected by local temperature variations associated with certain critical operating conditions. By providing a further embodiment of the system according to the invention in which the contact detection point is connected to a temperature sensor device, the necessary corrections are made possible.

In a further embodiment of the system according to the invention, the contact detection points of the hanger rod, the radio transmitter and the temperature sensor device are protected from the surrounding chemical environment by a chemically resistant resin, such as an epoxy resin.

In another aspect, the present invention relates to a method for evaluating the current distribution in cathodes and anodes of a metal electrodeposition plant, the method comprising the steps of:

equipping the hanger bar with at least one electrical probe by electrically connecting the at least one electrical probe to at least two contact detection points located on the cathode and anode hanger bars in an area defined by the electrical connection to the current bus bar and the first electrical connection to the respective cathode or anode;

calibrating the resistance of the cathode and anode hanger rods;

The current measurements are transmitted to a central computer via cables or radio transmitters;

interpreting the data via the central computer;

If a predefined abnormal phenomenon occurs, an alarm system connected to the central computer is activated;

Activate the optional device for disconnecting the electrode if an abnormality occurs.

In a further aspect, the present invention relates to a cathode or anode hanger rod for electrodeposition applications, wherein the cathode or anode hanger rod has a uniform resistivity and a regular geometry and has at least one microcircuit, wherein the at least one microcircuit is provided with a microprocessor connected thereto, wherein the microcircuit is connected to at least two detection points, wherein the at least two detection points are located in an area defined by an electrical connection to a current bus and a first electrical connection to the corresponding cathode or anode, wherein the microcircuit has an internal resistance circuit.

In a further aspect, the present invention relates to a method for evaluating the current distribution in cathodes and anodes of a metal electrodeposition plant, the method comprising the steps of:

Applying a microcircuit with an integrated microprocessor to each cathode and anode hanger rod by electrically connecting the microcircuit with an integrated microprocessor to at least two contact detection points located on each cathode and anode hanger rod in an area defined by an electrical connection to a corresponding current bus bar and a first electrical connection to a corresponding cathode or anode;

Calibrate the resistance of the cathode and anode hanger rods;

The current measurements are transmitted to a central computer via cables or radio transmitters;

interpreting the data via the central computer;

If a predefined abnormal phenomenon occurs, an alarm system connected to the central computer is activated;

Activate the optional device for disconnecting the electrode that exhibits abnormal behavior.

Some implementations of the invention will now be described with reference to the accompanying drawings, the sole purpose of which is to illustrate the mutual arrangement of the different elements with respect to the particular implementation of the invention described; in particular, the drawings are not necessarily drawn to scale.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 shows a schematic diagram of an electrode to electrode hanger rod coupling according to the present invention in a double electrical contact configuration.

FIG. 2 shows a schematic diagram of an electronic microcircuit according to the invention in a double electrical contact configuration.

DETAILED DESCRIPTION

In FIG1 , there are shown an electrode hanger rod 1 , an electrode 2 attached thereto, detection points 3 , 4 , 5 and 6 , current directions 7 , 8 , 9 , 10 and 11 , current busbars 12 and 13 , a microcircuit 14 equipped with a microprocessor.

In Figure 2, a schematic diagram of the electronic microcircuit is shown, indicating the area 15 corresponding to the circuit equivalent to the electronic circuit of the electrode hanger rod of Figure 1, the area 16 corresponding to the electronic circuit of the microcircuit, the detection points 17, 18, 19, 20, the resistors 23 and 24 corresponding to the various parts of the electrode hanger rod, the measurement points 21 and 22 of the potential difference of the microcircuit, and the applied resistors 25 and 26.

The following examples are included to illustrate specific embodiments of the invention, the utility of which has been largely demonstrated within the range of the values claimed. It should be understood by those skilled in the art that the configurations and techniques disclosed in the examples that follow represent configurations and techniques discovered by the inventor to work well in the practice of the invention; however, in light of this disclosure, those skilled in the art should appreciate that many changes can be made in the specific embodiments disclosed and still obtain like or similar results without departing from the scope of the invention.

Example

By applying the circuit according to the schematic diagram of Figure 2, a system for evaluating the current distribution of the cathode and anode is assembled. The method for calculating the current distribution in this specific case is based on the model expressed by the following formula. A is the voltage at point 17, C is the voltage at point 19, B is the voltage at point 18, and D is the voltage at point 20. M is the voltage at point 21, and N is the voltage at point 22. K is the resistance of the portion of the electrode hanger rod corresponding to between points 17 and 18. ^P* K is the resistance of the portion of the electrode hanger rod corresponding to between points 19 and 20. R is the value of the resistors installed between points 17 and 21 and between points 18 and 22, respectively. ^P* R is the resistance installed between points 19 and 21 and between points 20 and 22. I1 is the current between points 17 and 18, and I2 is the current between points 19 and 20.

Therefore, the potential difference between points M-N is proportional to (I1+I2). Knowing the total number of I, it is possible to deduce that R is equal to R1, R2...Rn, and therefore the individual currents.

The foregoing description is not intended to limit the present invention, which can be utilized according to different embodiments without departing from the scope thereof, and the scope of the present invention is defined only by the appended claims.

Throughout the description and claims of this application, the term "comprises" and its variations are not intended to exclude the presence of other elements, components and additional processing steps.

This specification includes discussions of documents, acts, materials, devices, articles and the like solely for the purpose of providing a context for the present invention. It is not intended to suggest or represent that any or all of these matters formed part of the prior art base or were common general knowledge in the field relevant to the present invention before the priority date of each claim of this application.

Claims (9)

1. A system for evaluating the current distribution in the cathode and anode of a metal electrodeposition plant, the system comprising: At least one electrolytic cell containing an electrolyte; A current bus, associated with the at least one electrolytic cell; Balance the secondary bus; Multiple cathodes and anodes are provided with cathode and anode hanger rods that are in electrical contact with them. The cathode and anode hanger rods have uniform resistivity and regular geometry. The hanger rods have a first terminal component adjacent to the current bus and a second terminal component adjacent to the balancing secondary bus. The hanger rods are adapted to hold the corresponding cathodes and anodes in position within at least one electrolytic cell. The cathode and anode hanger rods are equipped with at least one electrical probe, which is connected to at least four contact detection points located in areas on the cathode and anode hanger rods defined by electrical connections to a current bus and a balancing secondary bus, respectively, and a first electrical connection to the corresponding cathode or anode. 2. The system according to claim 1, wherein the cathode and anode hanger rods are equipped with at least one microcircuit, the at least one microcircuit having a microprocessor connected thereto, the microcircuit being electrically connected to the contact detection point. 3. The system of claim 2, wherein the at least one microcircuit is equipped with a radio transmitter. 4. The system of claim 3, wherein the contact detection point is connected to a temperature sensor device. 5. The system of claim 4, wherein the cathode and anode hanger rods are equipped with at least one microcircuit, the at least one microcircuit having the microprocessor integrated therewith. 6. The system of claim 5, wherein the microcircuit having the microprocessor integrated therewith, the contact detection point of the hanger rod, the radio transmitter, and the temperature sensor device are protected from the effects of the surrounding chemical environment by a chemical-resistant resin. 7. A method for evaluating the current distribution in the cathode and anode of a metal electrodeposition plant, wherein corresponding hanger rods are placed above the cathode and anode, wherein the method includes the following steps: The at least one electrical probe is assembled to the hanger rod by electrically connecting at least one electrical probe to at least four contact detection points, wherein the contact detection points are located in the region of the cathode and anode hanger rod defined by electrical connections to the current bus and the balancing secondary bus, respectively, and a first electrical connection to the corresponding cathode or anode. Calibrate the resistance of the cathode and anode hanger rods; The current measurement results are transmitted to the central computer via cable or radio transmitter; The data is interpreted through the central computer; If a predefined anomaly occurs, an alarm system connected to the central computer is activated; Optional device for disconnecting the electrode that is malfunctioning. 8. A cathode or anode hanger for electrodeposition applications, the cathode or anode hanger having a uniform resistivity and a regular geometry, and having at least one microcircuit, the at least one microcircuit having a microprocessor connected thereto, the microcircuit being connected to at least four detection points located in regions defined by electrical connections to a current bus and a balancing secondary bus, respectively, and a first electrical connection to a corresponding cathode or anode, the microcircuit having an internal resistive circuit. 9. A method for evaluating the current distribution in the cathode and anode of a metal electrodeposition plant, wherein corresponding hanger rods are positioned above the cathode and anode, wherein the method comprises the following steps: By electrically connecting a microprocessor-integrated microcircuit to at least four contact detection points, the microprocessor-integrated microcircuit is applied to each cathode and anode hanger rod, the at least four contact detection points being located in the region on each cathode and anode hanger rod defined by electrical connections to a current bus and a balancing secondary bus, respectively, and a first electrical connection to the corresponding cathode or anode; Calibrate the resistance of the cathode and anode hanger rods; The current measurement results are transmitted to the central computer via cable or radio transmitter; The data is interpreted through the central computer; If a predefined anomaly occurs, an alarm system connected to the central computer is activated; Optional device for disconnecting electrodes exhibiting abnormal behavior.