WO2017106982A1 - System for early detection of short-circuits and weak electrical contacts - Google Patents

Abstract

The invention relates to a system for the early detection of short-circuits and weak or non-existent electrical contacts of the electrodes (4) in electrolytic cells (7) for the electrowinning or electrorefining of metals, where said detection is performed on the basis of the change in colour of one of the elements of the system, which uses thermosensitive pigments, said system comprising: a means for detecting temperature change, formed by a plate (10) that uses thermosensitive pigments, said plate being arranged on a cathode rod (5), where said thermosensitive plate changes from a colour "N" of normal operation of the electrolytic cell (7) to a colour "A" with the increase in temperature, or, said plate using thermosensitive pigments changes from a colour "N" of normal operation of the electrolytic cell (7) to a colour "B" with a reduction in temperature; and a fixing means (12) for fixing said thermosensitive plate (10) to said cathode rod (5). The invention also relates to an associated method.

Description

 A SYSTEM FOR THE EARLY DETECTION OF SHORT CIRCUITS AND WEAK ELECTRICAL CONTACTS

DESCRIPTION

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a short circuit detection system and a method that allows monitoring of short circuits or weak electrical contacts or electrodes without electrical contact, in the cells of a large-scale real-time refinery. More specifically, the present invention relates to a system formed by a plate whose upper face is painted with a heat-sensitive paint that has the ability to change the color, due to the increase in temperature caused by a short circuit, said plate being placed in the upper portion. of a contact bar of a cathode, which adheres to it through a clamp that has a vent or visor, to be able to observe directly by the crew of inspection operators, whether or not there is a short circuit in any of the cathodes of The electrorefining cell. This system can be automated, by means of a color change monitoring of said plate, through a method that includes normal cameras connected to image processing means, so that the gang is informed of the exact place, where It is producing the short circuit. BACKGROUND OF THE INVENTION

 One of the incidents that causes the most damage in the electrorefining and electroobtention processes, are the short circuits between anodes and cathodes. These shorts are so common that they represent more than 5% of the total energy consumption of the plants that produce AAA copper cathodes.

 The reasons for these short circuits are mainly physical failures in the electrodes (bent anodes or cathodes), which causes them to touch and short.

 Depending on the voltage and current of the electrolytic cell, these short circuits can go from sudden heating of the cathode to even a fire.

One of the reasons why short circuits consume so much energy is because they cannot be detected immediately, as soon as contact between a cathode and an anode occurs. The reason for this is because in the electrorefining and electroobtention plants, it is a standard procedure to cover the electrolytic cells in production with opaque plastic covers. These covers fulfill the function of thermal insulation, to maintain the temperature of the electrolyte and also to capture the acid mist, in the case of electro-collection. A side effect of these covers is that they do not allow to see or detect high temperature points of the anodes and cathodes through thermal sensors. In some cases, replacing These opaque plastic covers are used small balls made of plastic such as polypropylene, polyurethane or other similar materials.

 To detect the short circuits, and as exemplified in Figures 1 and 2, the procedure is based on a group of workers of 4 or 5 operators (1) have to circulate through the narrow aisles (2) who proceed to remove the cover plastic (3) of a group of electrolytic cells, usually 6 or 8, and proceed to check each electrode (4) one by one with portable thermal cameras to detect which exceed 90 degrees, and that clearly indicates that there is a short circuit. Once a short circuit is detected, the operators (1) mark the cathode or anode shorted with paint, and withdraw to inspect the next surrounding area with another group of electrolytic cells.

 While inspecting the next group of electrolytic cells, the cells marked with short circuit are discovered, which impacts the temperature of the electrolyte, which tends to cool by precipitating impurities and thus generating quality problems in the cathodes.

Once the inspection of the set of selected cells is finished, the same group of operators proceeds to remove one by one, each electrode in short circuit and replace it with one in good condition. Because of this, the detection and correction of short circuits is very slow. Many times in the common practice of a plant, there is only one group of inspection operators per work shift, and if we consider that the ship Electrorefining of the large mining companies, it has 2000 electrolytic cells, it is clear that this procedure is extremely slow and discreet.

 As shown in Figure 3, a cathode bar (5) is in contact with an electric busbar (8) mounted in a set on the upper wall face of the electrolytic cell (7). In this case, the contact area (6) is full, since the cathode bar (5) and the upper end of the electrical distribution bar (8) are in contact. While it is true, that it is possible to have a good contact, sometimes, for example, when the cathodes or anodes are bent there is a contact between them, and therefore, a short circuit that increases the temperature of the cathode bar (5). On the other hand, in figure 4, a cathode bar (5) is shown which is in contact with an electric busbar (8) mounted in a set on the upper wall face of the electrolytic cell (7). In this case, there is a slack in the contact zone (6) and therefore, the flow of electricity is interrupted in the other electrodes of the circuit. On other occasions, this lack of contact is due to dirt that may be in the contact area (6) or under the cathode bar (5)

Another problem that occurs in the electroobtention and electrorefining plants refers to the fact that some of the cathodes do not make contact, because their bar is bent or the contact is dirty. Therefore, it is also essential to have some means of early detection of a fault of an electrical contact. In this case, contrary to what happens in a short circuit where the temperature rises, when the bar of a cathode is without contact, then its temperature drops to around 45 ^Q C and is lower than that of the cell and the rest of the electrodes that are located around 65 ^Q C and more

In the state of the art, several monitoring methods have been tried for short circuits in electrolytic cells. For example, in document DE 2524376 entitled "Detection of short circuits between electrodes of electrolytic cell - by detectors which opérate by magneto-motor forced positioned by an automatically controlled overhead carriage", (Kobayashi et. Al), published dated 09 December 1979, discloses a short-circuit detector system between the anodes and cathodes, placed individually in an electrolytic cell, in which each comprises a switch that is kept open by an external magnetic field, linked to a permanent magnet by an axis used to adjust the relative positions of the switch and the magnet. When a short-circuit of the permanent magnet is detected, a force opposite to that of the external magnetic field is applied, closing the switch and causing the lighting of a light, whereby the illumination is an indication in the detector, that there is a short-circuit. The detectors are mounted on a horizontal bar connected to a car traveling on rails that crosses above a bank of electrolytic cells. This car is connected to the control circuit that allows you to lift the detectors from the electrodes and move on to the next cell automatically if no short circuit is detected at any given time

US 2005/217999 entitled "Wireless electrolytic cell monitoring powered by ultralow bus voltage" (You et al.), Published on October 6, 2006, discloses that in a typical copper refinery that produces 300,000 tons of copper cathodes at year, in some cases there will be up to 1440 electrolytic cells, each with 46 anodes and cathodes, for a total of 131,000 pieces suspended in the cells. In a traditional copper refinery, each cathode and each anode is electrically connected to the refinery's current supply system, through two or more contact points on the anode support ears and cathode suspension bars . This means that there can be a total of more than 260,000 electrical connections (that is, two for each anode and two cathode two times the number of cathodes and anodes). A critical point for the efficient operation of the refining process is the absence of short circuits between the anodes and cathode blanks. Short circuits can occur if the anodes and cathodes are misaligned or if copper deposits in the cathode grow unevenly and in contact with the anode. When short circuits occur, the desired copper coating process is interrupted and the efficiency of electrical use decreases. Consequently, short circuits result in the decrease of the voltage difference across the anodes and cathodes. Therefore, the Effective operation of the refining process is the absence of open and short circuits between the anodes and cathodes. Open circuits, on the other hand, can occur if there is a bad contact between the power supply and the anodes or cathodes. When the circuits remain open, the efficiency of the use of electrical energy decreases. The system disclosed in this document uses a transmission rate of 76.8 k bits / second or greater; It has a transmission and reception range of approximately 200 feet or more; three or more 10-bit A / D channels; an ambient operating temperature of approximately -10 ^Q C to 85 ^Q C; a resolution of the digital temperature sensor of ± 0.0615 ^Q C or greater; and uses an LED output to communicate data to cell phones, such as cell voltage. Because it is based on a microprocessor, it can also be programmed to compress and filter the data signals before transmission, the process data of the cell hall and recognize the deviations of the thresholds from the default values, analyze the Electrical connection and quality in electrolytic cells, and implement the wireless communication protocol. A preferred way for signal output is through LED, to communicate the state of the electrolytic cell. More specifically, the cell voltage, which is an important parameter, and that visually indicates to the operators to locate the problem. For example, the cell voltage can be linearly converted to a LED flicker frequency so that a short circuit in an electrolytic cell can easily be identified by a operator, visually comparing the flickering frequency of the various LED outputs. In another preferred embodiment, multiple outputs can be used, with different colors representing different sensor conditions, using this type of LED. These LED outputs can be used for diagnostic purposes such as transmission monitoring and short circuit identification. In another preferred embodiment, audible outputs are also provided to communicate cell data. These types of indicators allow operators to focus the remote efforts of a large population of electrolytic cells, and focus on those electrolytic cells that need more immediate attention.

In US 3,809,902 it discloses a method and apparatus for detecting the existence of short-circuit conditions between adjacent electrodes located in an electrolytic cell. Electrolytic cells have a plurality of anodes and cathodes, which are substantially immersed in the electrolyte and short-circuit conditions caused by physical contact between adjacent electrodes do not rarely develop. In this document, the detection of incipient short-circuit conditions in an electrolytic cell is disclosed, by scanning the surface of the cell with an infrared detection apparatus under scanning conditions that allow the detection of thermal anomaly, created by the existence of the short circuit condition. The method and the apparatus are useful for exploring a large number of electrolytic cells found in a power plant. production, so that each of the cells can be evaluated quickly, to determine the possible existence of incipient short circuit conditions. To carry out this inspection, the apparatus comprises a carriage with longitudinal and transverse rails mounted above the cells, for example on the roof of the cell hall, which carry a carriage with infrared sensors and which moves in a programmed manner by over an inspection area of the electrolytic cell building. When an increase in temperature is detected, the electronic circuits located inside the car send a signal to a control room.

US 2007/0284262 discloses a method of detecting short circuits and poor contacts in an electrolytic cell. The cell comprises an electrolyte container with at least one pair of anodes and cathodes, the container comprises a lateral inlet of the electrolyte flow and a lateral outlet of the electrolyte flow, communication transmission means and electrical transmission, the method comprising: ( a) passing an electric current of a pre-determined amperage through the cell: (b) measuring the voltage drop in the cell on the inlet side of the electrolyte flow and on the outlet side of the electrolyte flow; (c) compare the electrolyte voltage of the input flow side against the electrolyte voltage of the output flow side, and (d) compare the voltage of the electrolyte input flow and the electrolyte output flow, with respect to a predetermined voltage value. WO 2014/076374 entitled "An arrangement for monitoring a current distribution in an electrolytic cell", (Rantala et al.), Dated May 22, 2014, discloses a provision for monitoring a current distribution in the cell electrolytic, it comprises a plurality of current sensors arranged in the acid mist capture hood in places where, when the acid mist capture bell is placed in its position above the cell, they are aligned with the locations of the cathode electrodes. The arrangement comprises an elongated removable hood disposed above an electrolytic extraction cell to capture the acid mist of the electrolytic cell, a plurality of current sensors arranged in the acid mist capture hood in places where, when the hood of Acid mist capture is in a position of use, they are aligned with the locations of the cathode electrodes between a plurality of transverse anode electrodes and a plurality of transverse cathode electrodes, alternately located in the longitudinal direction direction of said electrolytic cell , each of said plurality of current sensors being arranged to measure a direct current flowing in the respective aligned cathode electrode, and means for indicating the cathodic electrodes that cause an unequal distribution of direct current in the electrolytic cell, based on the sensor measurements of current. The indicating means comprise a plurality of alarm indicators, provided in said acid mist capture hood, in locations of said plurality of cathode electrodes to indicate locally whether the electrode or electrodes of the cathodes are causing an unequal distribution of direct current in the electrolytic cell. The indicating means comprise an indicator panel disposed in the capture hood of the acid mist or the electrolytic cell, to indicate and identify any electrode or cathode electrodes, which are causing an uneven direct current situation in the electrolytic cell. Furthermore, the arrangement comprises means for activating said plurality of current sensors with electrical energy through electrically conductive busbars, which are arranged to supply electrical current to said plurality of anode and cathode electrodes in said electrolytic cell.

US 5483068 entitled "Use of IR (thermal) imaging for determining cell diagnostics" (Moulton et al.), Published on January 9, 1996, discloses a method for detecting a defective electrochemical cell, by non-invasive means before assembly in a battery that comprises several cells. The method that detects defective cells by detecting and detecting variations in the intensity level of the infrared radiation emitted from an outer surface of the cell. The exploration and detection is carried out by the emission of infrared detection energy in a range of 2 to 12 μιη (microns), which comes from the main surface of the cell. Variations are recorded as a function of geometric variables indicative of the geographical position of the variations. The method for determining a defective electrochemical cell comprises scanning and detecting variations in the intensity level of the infrared radiation emitted from a main outer surface of the cell, coextensive with a main surface of an electrode of said cell, said scanning and detection is carried out by detecting infrared energy in a range of 2 to 2 μιη emitted from the outer surface. The method further comprises scanning the outer surface, to detect such variations in the intensity level of the infrared radiation of the outer surface compared to the intensity of the infrared radiation, emitted by an outer main surface of another cell that is not defective and is used as a standard. In another embodiment, the method for determining a defective electrochemical cell comprises: a) initially thermally stabilizing the cell to be tested; b) discharge from the cell a current that is relatively constant and varies by no more than about 10% during discharge; c) scanning to detect the infrared response during or immediately after said scan discharge and to detect the variation in the intensity level of the infrared radiation, emitted from a main outer surface of the cell, making it extensive with a main surface of a electrode of said cell, and explore the detection that was carried out by infrared energy in a range of 2 to 12 μι emitted from the outer surface. Document DE 102005005819 entitled "Lead anode for recovering zinc and / or copper comprises heat recognition elements having surface region provided with thermo-chromic lacquer" (Walk, Hartmut), dated March 2, 2006, discloses lead anodes that are used in electrolytic processes in the zinc and other valuable metals industry, where a large number of lead anodes are placed in close proximity to the aluminum cathode sheets, in electrolytic cells, in a bath with a sulfuric acid zinc leach. In large electrolysis vessels up to 10,000 lead plates or more are found in cells, such as anode and cathode plates. The anodes as cathodes are perpendicular in the baths of the electrolytic cells. The anode plates operate as resistant electrical conductors of zinc leaching and a substantial current density of 400-600 amps per square meter is applied. For the deposition of zinc the necessary voltage is 3400 kilowatt hours per ton, of which approximately 1/3 is converted to heat, so that the electrolyte has to be cooled to the optimum bath temperature of 30 ^Q C to 40 ^Q C to obtain a better energy efficiency. The cathode sheets capture zinc as a function of the current density at regular intervals, and the zinc coating is mechanically separated from the cathode sheets generally made of aluminum. Due to the narrow arrangement between the anode and the cathode, the aluminum or copper sheets of the latter can cause a number of problems and cause short circuits. A short leads naturally to an increase in current flow and at a high temperature. The short circuits involved in the anode can overheat in the worst case until destruction. In the latter case, the conductivity of the assembly in the connection is broken, so that the connection of the anode plate is ineffective. At the same time, the anode plates that remain in the process become stronger and the risk of overheating increases. In any case, here also suffers the overall performance of the recovery of zinc or copper. To deal with these problems, in the prior art a thermal camera monitoring is carried out. A certain number of these thermographic cameras are passable and placed in devices that span more than 100 meters. While these thermal cameras can create a relatively accurate image, at the time when the anodes increase their temperature, however, this can only be a function of time to extraction needs. Consequently, appropriate assessments occur only once to three times in 24 hours. Therefore, overheating with the corresponding detrimental effects for several hours can occur without being detected in time. Unlike the conventional approach with thermal cameras, infrared cameras or thermal cameras, according to the invention direct access to the exact heat detection element specifically directed to lead lead anode plate is possible. This object is also achieved by an arrangement for the recovery of zinc, from leaching of zinc and / or copper from copper leaching, inside a bath of an electrolytic cell with a plurality of anode lead plates and cathode sheets, which are installed in the cell in parallel and arranged alternately with each other. Through the thermal sensing element, in particular, by the area of a surface coated with thermochromic paint, for example the section of an ear of the lead anode plate, has a color at a certain working temperature, but if it exceeds a predetermined temperature value, an indication of color change will appear for a higher temperature by a certain current flow, and therefore, it may be lower that that lead anode plate may then be suffering a short circuit. Preferably the thermochromic paint is used for this purpose, in which the color change is reversible. This means that a color change occurs, it also means that the temperature will also return to the previous value, thereby indicating that the temperature has returned to its normal range. After the repair of the lead plate that forms the anode, detecting and repairing the defect, and that the operation of the lead plate in the recovery of zinc or copper, continues unchanged, then the thermochromatic paint has complied with its objective. It is preferred that the thermochromic coating begins to change above 55 ^Q C, which is significantly higher than the normal operating temperature. On the other hand, it is preferred that this coating also temperature well below 80 ^Q C, since first negative effects on lead anode plates can already occur. A Particularly preferred temperature envelope is tested, it is around 65 ^Q C to 70 ^Q C, especially 68 ^Q C. Outside and above the zinc leach bath of the anode lead plates, each have a heat sensing element, which is located on a portion of the surface. This heat sensing element is in one of the embodiments, which is formed by a surface coating with a thermochromic paint. This thermochromic paint is selected so that it changes color at 68 ^QC . Below this temperature it has a first color, which reaches a relatively low level of attention to an observer. Above the temperature changes that are above the temperature of 68 ^Q C, the thermochromic paint changes a second state of bright colors, for example, a bright orange color. Therefore, this second color has a higher value for observer attention.

This last solution is the closest to the present application. However, directly painting a cathode with a thermosensitive paint has a fairly low durability, because they are subjected to an environment with acid mist, which means that such mist affects the durability of the paint by degrading it quickly. In fact there are no cathodes painted on the market for the same reason. In addition, the cathodes must be removed or removed from the cell, during each harvest and all lifting and transport systems of the Refinery ship, use the ears as a means of hooking, which is why any coating by way of a simple paint is constantly damaged.

 All this, acid mist and electrode manipulation, causes the heat-sensitive paint to suffer damage in a short time, and therefore, it is necessary to repaint the contact edge regularly. However, to achieve a good functioning of this paint, it is necessary to sand and prepare the edge until the rest of the original paint is completely removed or removed, so that the pigment comes into direct contact with the copper and changes color according to the real ear temperature. On the contrary, repainting with thermochromatic paint of a semi-scraped ear will generate a layer of irregular thickness that will distort the actual temperature of the copper ear of the cathode.

 In general, in the rest of the documents of the state of the art, there are systems to detect the short circuits that occur in an electrolytic cell, but they require sensors, controllers, movement means and specially designed electronics, to meet this objective . However, all these systems are complex to implement and, it is ultimately for this reason, that they are not implemented in practice, by the mining companies in the refinery and electrorefining ships.

SUMMARY OF THE INVENTION The present invention consists of a small plate that adheres to the upper part of the cathode ears, which is fixed to the contact edge, by means of a clamp that has a vent or visor at its top, in order to observe a change of color directly by the crew of inspection workers, if any of the cathodes is short-circuited, or if the anode rod and the electrical support of the cell busbar have no electrical contact, or This is very poor, so it is also necessary to visualize this situation.

 The plate can be made with a plastic that has a thermochromic or thermosensitive pigment, which changed its normal color to a striking color, when there is a short circuit, or change color when the cathode lowers its temperature. Alternatively, it is possible to use a plate, preferably metal, whose upper surface is painted with thermochromic or thermo-sensitive paint, either to detect short circuits, or to detect cathodes that do not have electrical contact, or it is very poor.

Thermochromatic pigments can be used within the content of the pellets that are used in the manufacture of plastic parts and designed to change color at a certain temperature. In the case of metal type plates, the paint changes from a known base color, to a high contrast color when a short circuit occurs, since the short one raises the temperature of the ear of the cathode in contact over 90 ^Q C. YES is considered that the normal operating temperature of an electrorefining or electroobtention cell is only 65 ^Q C, the result will be that the short bar will clearly stand out from the rest of the electrodes, being the only one that changes color to a high contrast one , or, if the temperature drops to 45 ^Q C, given the signal to the operator that there is a lack of contact, or, this is very weak.

 The plate can be attached to the cathode ear in different ways, with brackets, clamps or other special mechanical elements, which adhere to the hanging bar, which is usually copper.

 Another advantage is that the short circuits can be detected with common cameras, such as security cameras, and the entire ship can be monitored in real time. If you also associate an image recognition software that automatically detects the color change, so it will be possible to automate the monitoring and issue an alarm to the shorts correction crew indicating the exact location of the problem. This can be implemented when other acid mist capture systems are used in the cells, such as plastic balls or polyurethane balls, which are placed on the surface of the electrolyte.

Pigments for industrial use, which can be placed on the pellets to make plastic strips, or heat-sensitive paints, have the property of changing color according to the temperature at which they are exposed and can be manufactured to have specific colors and change from coloration at a defined temperature, for example at 90 degrees which is the temperature that indicates the start of a short circuit. Thanks to this property, the cover can cover the cells in production and maintain a known regular color (for example, white) with operating temperatures of the cell, between 65 to 80 ^Q C. If a short circuit occurs, the exact place where it occurs, it will rapidly change color, for example, to a bright red, since under the cover the area where the cathode is in short circuit, the temperature will rise rapidly to 90 ^Q C or more, while the rest of the surface will remain white.

 When the crew of workers inspect the cells that are normally covered by the covers, especially in electrorefining cells, you will quickly know if there is a short-circuit or not, and if so, you will quickly identify which cathode is with problems, without needing take measurements, or use portable infrared cameras, to locate the problem.

Another advantage of the present invention is that the short circuits can be detected with common cameras, such as security cameras, and the entire electrolytic cell spacecraft can be monitored in real time, provided they have translucent covering means, or, As it is mainly used in electroobtention, balls on the surface of the electrolyte to prevent the emanation of acid mist from the environment. If an image recognition software is associated with common cameras, that automatically detects the change of color, it will be possible to automate an alarm to the operators, who will now only be dedicated to correct short circuits indicating the exact location of the problem. Therefore, the present invention also proposes a method for the control of short circuits, in the aforementioned cases.

BRIEF DESCRIPTION OF THE DRAWINGS

 The accompanying drawings are included to provide greater compression and explain the principles of the present invention and are part of the description.

 Figure 1 shows a perspective view of a ship of electrolytic cells, where the operators are located in the corridors and must pass between them, cells to go raising the covers and detect with infrared cameras whether or not there is a short circuit and in What a specific place.

 Figure 2 shows a perspective view of a ship of electrolytic cells, where one of the operators is lifting the cover to detect whether or not there is a short circuit and in what specific place.

Figure 3 shows a sectional side view of a cathode bar that is making contact with the current transmitter bar, but that could be making a short circuit, with one of the adjacent anodes. Figure 4 shows a sectional side view of a cathode bar that is not making contact with the current transmitter bar, affecting the electrical propagation of the rest of the cell electrodes.

 Figure 5a shows a perspective view of the thermosensitive plate, which is used in the system of the present invention.

 Figure 5b shows a perspective view of two modalities of heat-sensitive plates, which are used in the system of the present invention.

 Figure 6 shows a bottom perspective view of a first embodiment of the system of the present invention where the plate is formed of a plastic material, which has heat sensitive pigments.

 Figure 7 shows a top perspective view of a first embodiment of the system of the present invention wherein the plate is formed of a plastic material, which has heat sensitive pigments.

 Figure 8 shows a bottom perspective view of a first embodiment of the system of the present invention wherein the plate is formed by a heat conducting material having a layer of paint on its upper surface, containing heat sensitive pigments.

Figure 9 shows a top perspective view of a first embodiment of the system of the present invention in which the plate is formed by a heat conducting material having a layer of paint on its upper surface, which contains heat sensitive pigments. Figure 10 shows a front view in section and its corresponding side view with the cutting lines, of a first embodiment of the system of the present invention, mounted on a cathode bar.

 Figure 1 1 shows an exploded perspective view of a first embodiment of the system of the present invention and the cathode bar where it will be installed.

 Figure 12 shows a top exploded perspective view of a first mode of the system of the present invention, where two systems, one for short-circuit and non-contact detection, in addition to the cathode bar where they will be installed.

 Figure 13 shows a top perspective view of a first embodiment of the system of the present invention, where two systems, one for short-circuit and non-contact detection, are installed in the cathode bar.

 Figure 14 shows a top perspective view of a second embodiment of the system of the present invention.

 Figure 15 shows a top perspective view of a third embodiment of the system of the present invention.

 Figure 16 shows a top perspective view of a fourth embodiment of the system of the present invention.

Figure 17 shows a top perspective view of a fifth embodiment of the system of the present invention. Figure 18 shows a top perspective view of a metal electro-obtaining cell using one of the embodiments of the system of the present invention.

 Figure 19 shows a schematic view of the elements used, automatic monitoring and real time, in the types of cells shown in Figure 18.

DESCRIPTION OF THE INVENTION

The present invention relates to a system for detecting short circuits and weak electrical contacts or electrodes without electrical contact, by changing the colors of heat sensitive pigments. The system consists of a plate that changes color when the temperature in the contact bar of the cathode increases by a value close to 90 ^Q C due to a short circuit, or it changes to a certain color, when the temperature drops around 45-C due to a bad electrical contact or that the cathode rod is without electrical contact. The plate is positioned on the upper face of the cathode bar and is fixed through fixing means, such as enclosures, clamps or other mechanical fasteners.

Referring to Figures 5a and 5b, if the electrolytic cell, both for electroobtention and electrorefining, is functioning correctly, then the temperature at the electrodes will be around 65 to 80 ^Q C. However, if the temperature of the electrodes rises to 90 ^Q C or more, means that a short circuit is occurring. On the other hand, if the temperature drops to around 45 ^Q C, it is a sign that some electrode stopped making contact, interrupting the current to the other electrodes. Therefore, in any of the two situations, it is necessary to have some element of low cost, which allows to identify and locate exactly the electrode that is in trouble. For this, the present invention proposes to place on the upper face of the cathode bar ( 5) a plate (10) that allows to detect these problems through the color change in it.

 In a first embodiment, the plate (10a) is made up of a plastic that contains heat-sensitive particles, or the plate can be made of a good heat-conducting material, such as a metal, whose upper face has a film with paint heat sensitive In both cases, it is possible to obtain, through different manufacturers and distributors in the world, heat sensitive pigments that are of a "N" or normal color, for example white, and that change to a striking "A" color of high temperature, by example, within the red spectrum, to determine the short circuits. It is also possible to obtain heat sensitive pigments that are of a "N" or normal color, for example white, and that change to a "B" color of low temperature, for example, within the green spectrum, to determine the lack of contact electric.

However, if one wishes to place on a cathode bar (5) only one heat-sensitive plate (10), or two heat-sensitive plates (10), one for detect short circuits or a bad electrical contact, then it will be necessary to look for some means of fixing (12) of the thermosensitive plate (10) to the cathode bar (5).

In a first embodiment, as shown in Figures 6 and 8, the fixing means (12) is formed by a closed housing (12a) having a recessed body (1 1) that wraps around the cathode bar (5) both on its lateral faces, lower face and upper face, leaving a central cavity (16) that crosses said closed housing (12a), from its front face towards its rear face, said central cavity (16) having a clearance to fit both the cathode bar (5), such as the heat-sensitive plate (10). The heat-sensitive plate (10) is placed on the cathode bar (5), close to the cathode sheet (9). When the heat-sensitive plate (10) and the closed housing (12a) are in place, the lower wall has a lower perforation (17), usually threaded, to accommodate a screw (15), which is tightened to fix The housing and the plate. So that the color change of the heat-sensitive plate (10) can be visualized, the closed housing (12a), has on the upper face of the hollowed body, an upper hollow (14), smaller in contour than the heat-sensitive plate (10 ), so that it becomes a viewer. In cases of environments that are very aggressive, it is possible to place a translucent plate (13) that can be made of glass, translucent plastic, translucent polycarbonate or the like, to protect the plate from said environment. Figures 8 and 9 are similar to Figures 6 and 7, where the same previous modality is shown, but where the plate is a metal plate painted with heat-sensitive paint (10b), which is the second type of plate The present invention.

 The ability of the enclosed housing (12a) to house the cathode bar (5) and the heat-sensitive plate (10), can be seen in Figure 10. First, in the image on the right, a side view is shown of the cathode bar (5) and the closed housing (12a), which have a cut line, which corresponds to the image on the left. In the latter, it is observed that both the cathode bar (5) and the thermosensitive plate (10), are correctly fixed and joined, so that if the cathode bar (5) is heated, it is transferred to the plate heat sensitive (10), making it change color. Fixing occurs by tightening the screw (15) in the lower hole (17), which also has a thread. Obviously, for people versed in the art, the arrangement of the fixing means, such as a screw and thread drilling, can be placed anywhere in the contour of the hollowed body (1 1) of the closed housing ( 12a).

As noted in the preceding paragraphs, the heat-sensitive plate (10) and the closed housing (12a), which make up the system of the present invention, is placed in the cathode bar (5), as shown in the figure eleven . However, with one system it is possible to obtain one of the two desired conditions of knowing, that is, an increase in temperature due to a short circuit, or a decrease in temperature due to a contact failure. Therefore, if it is necessary to know both conditions, it will be necessary to place two systems, with different heat-sensitive plates (10), one that has heat-sensitive pigments that detect high temperatures and one that has heat-sensitive pigments that detect low temperatures, according to either of the two modalities of plates (10), a plate formed by plastic with heat sensitive pigments (10a) and another plate formed with a metal and painted on its upper face, with a paint that has heat sensitive pigments (10b). Therefore, in figure 12, an exploded view of two systems of heat-sensitive plates 10 and closed housings (12a) are shown which are placed one next to the other, first one and then the other, as shown in figure 13 .

In the event that an assembly is desired, carry out an independent assembly, or, it is necessary to intervene only the system closest to the cathode plate (9), avoiding having to remove both systems, it is possible to carry out this invention, with a housing Side mount In figure 14, a second embodiment of the invention is shown in which the fixing means (12) is formed by a lateral housing (18), in which it has a hollowed and open lateral body (19), wherein a from its side walls it has been removed, to leave it independently, as a removable side wall (20). As in the first mode, the The housing has an upper window (14), to visualize the color change in the heat-sensitive plate (10). Also, if there is a very aggressive environment, it is possible to place a translucent plate (13) that can be made of glass, translucent plastic, translucent polycarbonate or the like, to protect the plate from said environment.

 In this case, the side housing (18) is mounted on the side of the cathode bar (5), ensuring that the heat-sensitive plate (10) is adjusted and aligned with the upper window (14). Once this has happened, the removable side wall (20) is passed through the upper groove (21), until it meets the edge of the lower floor (22) of the hollowed and open side body (19). After that, the screw (15) is introduced into the side hole (17), which usually has a thread, and then, said screw (15) is tightened until the entire system is fixed.

A third embodiment is shown in Figure 15, wherein the fixing means (12) is formed by an upper housing (23), in which it has a hollowed and open lower body (24), where its lower wall has been removed, to leave it independently, as a removable bottom wall (25). As in the first and second modalities, the housing has an upper window (14), to visualize the color change in the heat-sensitive plate (10). Also, if there is a very aggressive environment, it is possible to place a translucent plate (13) that It may consist of glass, translucent plastic, translucent polycarbonate or the like, to protect the plate from said environment.

 To mount from the top of the cathode bar (5), the upper housing (23) is placed on said cathode bar (5) and lowers until the heat-sensitive plate (10) is contacted, making sure that it is tight and aligned with the upper window (14). Once this has happened, the removable bottom wall (25) is passed through the lower side groove (26), until it meets the lower side edge (27) of the hollowed and open lower body side wall (24 ). After that, the screw (15) is introduced into the lower hole (17), which usually has a thread, and then, said screw (15) is tightened until the entire system is fixed.

A fourth embodiment is shown in Figure 16, where the heat-sensitive plate has a rear extension (50) and a front extension (51), which contain a first rear slot (28) and a second front slot (29), for receiving the fixing means (12). In this fourth embodiment, the fixing means (12) are formed by a first rear clamp (52) that fits into the first rear groove (28) and by a second front clamp (53) that fits into the groove (29). The first rear clamp (52) is formed by a plate that has the same width as the first rear groove (28) and a thickness equal to the depth of the first rear groove (28). The first rear clamp (52) is formed by said folded plate, it has an upper rear open side portion (38), bending to form a rear upper portion (30), bending to form a rear continuous side portion (36), bending to forming a rear floor portion (37), bending to form a lower rear open side portion (39). From the upper rear open side portion (38) emerges perpendicularly thereto a rear upper projection (33) having a upper rear central perforation (54), and from the lower rear open lateral portion (39), emerges perpendicular to This is a lower rear projection (32) having a lower central rear perforation (44). To tighten the first rear clamp (52), it is necessary that the upper rear portion (30) be placed in the first rear groove (28), and after that, the rear screw (46) is passed through the upper rear central perforation (54) and the lower rear central perforation (44), being tightened using the rear nut (48). The entire first rear clamp (52) wraps the heat-sensitive plate (10) and the cathode bar (5), thus generating a first fixation in this mode.

The second front clamp (53) is formed by a plate that has the same width as the first front groove (29) and a thickness equal to the depth of the first front groove (29). The second front clamp (53) is formed by said folded plate, it has an upper front open side portion (40), bending to form a front upper portion (31), bending to form a front continuous side portion (42), bending to form a front floor portion (43), bending to form a lower front open side portion (41). From the lower front open side portion (41) emerges perpendicularly thereto a front upper projection (34) having a central perforation (54), and from the lower front open side portion (41), emerges perpendicular to it a lower front projection (41) having a central perforation (55). To tighten the second front clamp (53), it is necessary that the upper front portion (31) be placed in the second front groove (29), and then the front screw (47) is passed through the upper front central perforation (45) and the lower front central perforation (45), being tightened using the front nut (49). The entire second front clamp (53) wraps the heat-sensitive plate (10) and the cathode bar (5), thus generating a second fixation in this fourth mode.

A fifth embodiment is shown in Figure 17, where the heat-sensitive plate has a rear extension (50) and a front extension (51), which contain a first rear slot (28) and a second front slot (29), for receiving the fixing means (12). In this fifth mode, the fixing means (are formed by a first rear clamp (52) that fits in the first rear groove (28) and by a second clamp (53) that fits in the groove (29). The first rear clamp (52) is formed by a plate that has the same width as the first rear groove (28) and a thickness equal to the depth of the first rear groove (28). The first rear clamp (52) is formed by said folded plate, it has an upper rear open side portion (38), bending to form a rear upper portion (30), bending to form a rear continuous side portion (36), bending to forming a rear floor portion (37), bending to form a lower rear open side portion (39).

 The second front clamp (53) is formed by a plate that has the same width as the first front groove (29) and a thickness equal to the depth of the first front groove (29). The second front clamp (53) is formed by said folded plate, it has an upper front open side portion (40), bending to form a front upper portion (31), bending to form a continuous front side portion (42), bending to forming a front floor portion (43), bending to form a lower front open side portion (41).

From the upper rear open lateral portion (38) and from the upper open front lateral portion (40) a first upper perpendicular projection (56) emerges perpendicular thereto having a superior central perforation (57). From the lower rear open side portion (39) and from the lower front open side portion (41), it emerges so perpendicular to these a second lower perpendicular projection (58) having a superior central perforation (57). To tighten the first rear clamp (52) and the second front clamp (53), it is necessary that the upper rear portion (30) be placed in the first rear groove (28) and that the upper front portion (31) it is placed in the second front groove (29) and after that, the lateral screw (60) is passed through the lower central perforation (59) and the upper central perforation (57), said screw (60) being tightened using the front nut (51), thus generating a single fixation in this fifth mode.

 The fixing means (12), such as enveloping housings, clamps or other mechanical fixing elements, according to the embodiments, such as, for example, the closed housing (12a), the upper housing (23), and the fixing systems a through the first rear clamp (52) and the second front clamp (53), they are generally formed of metal, and can even be molded in plastic that have heat sensitive pigments, such that in the latter case, the complete assembly can indicate the existence of a short circuit or a disconnection of any of the electrodes.

However, in some cases, when there are no plastic covers, but, for example, balls (66) floating on the electrolyte, as shown in Figures 18 and 19, the automated monitoring of color and time change real, it can be carried out quite simply And at a low cost. This requires that the heat-sensitive plates (10) attached to the cathode bars (5) change their color "N" (normal temperature) to a color "A" (high temperature), or change their color " N "to a color" B "(low temperature).

 For this, the present invention proposes a monitoring method, which uses the thermosensitive plate systems (10) and their fixing means, installed the cathode bars (5). In Figure 1 9, it can be seen that the heat-sensitive plates (10) are placed on the cathode bars (5), fixed by a closed housing (12a) having a window (14), which are being monitored by at least one Conventional video camera (62), which transmits the image to a control center, where there is a computer (63) that acts as a monitor to display the images captured by the video camera (7). A surveillance operator in the control center, being in front of the computer (63), can notice that a short circuit is being generated by the color change from "N" to "A" of a heat-sensitive plate (10) that is in a certain cathode bar (5). This surveillance operator can warn the plant operator (1) by radio, informing the specific place where the short circuit is taking place, so that the actions tending to change the electrodes (4) of a certain electrolytic cell (7) are taken. .

This system can be automated, if the computer (63) has an image analysis software, which allows to detect the color change from "N" to "A" or "N" to "B", and to inform through a means of transmission wireless (64) to the plant operator (1), the specific place where the short circuit is occurring.

 To operate the short-circuit monitoring system in an electrolytic cell building, the following method is proposed:

(a) placing a system formed by a thermosensitive plate (19) attached thereto by means of fixing on an electrolytic cell (7) where said thermosensitive plates (10) are designed to be placed on the cathode bars (5). have a uniform "N" color in each of them, when the operating temperature of the electrolytic cell (7) is in a range between 65 to 80 ^Q C, and where said heat-sensitive plates (10) change to a color "A" when there is a temperature increase to 90 ^Q C or more, or when they change to a color "B" when there is a temperature decrease from 45 ^Q C;

 (b) capture the image of a plurality of heat sensitive plates (10);

 (b) transmit the image of the heat-sensitive plates (10) to a computer (63), located in an operating room;

 (c) process said image to determine if said cover (2) has changed color from "N" to "A", or "N" to "B"; Y

(d) transmitting the location of the electrolytic cell (7) associated with the transmitter via wireless transmitter (64) to a plant operator (1) heat-sensitive plates (10) that have changed a color, in a capture area of the processed image (5).

Claims

 one . - A system for the early detection of short circuits and weak electrical contacts or without electrical contact in the electrodes (4) in electrolytic cells (7) of electro-obtaining or electro-refining of metals, where said detection is carried out by changing colors of one of the elements of the system, which uses heat sensitive pigments;  CHARACTERIZED because said system comprises:  a temperature change detector means, formed by a plate (10) that uses heat-sensitive pigments, which is located on a cathode bar (5), wherein said heat-sensitive plate changes from a normal "N" operating color of the electrolytic cell (7) to a color "A" with increasing temperature, or said plate that uses heat sensitive pigments that changes from a normal "N" operating color of the electrolytic cell (7) to a color "B "with temperature decrease; Y  a fixing means (12) for fixing said heat-sensitive plate (10) on said cathode bar (10).  2. - A system according to claim 1, CHARACTERIZED in that said heat-sensitive plate (10) is formed by plastic having heat-sensitive pigments. 3. A system according to claim 1, CHARACTERIZED in that said heat-sensitive plate (10) is made of a heat conducting material, in which it has a paint film with heat-sensitive pigments. 4. - A system according to claim 3, CHARACTERIZED in that said heat conducting material is a metal.  5. - A system according to any of claims 1 to 3, CHARACTERIZED because the fixing means (12) are made of plastic having heat sensitive pigments.  6. - A system according to any of claims 1 to 3, CHARACTERIZED because the fixing means (12) are formed of metal.  7. - A system according to any of claims 1 to 6, CHARACTERIZED because the fixing means (12) is formed by a closed housing (12a) having a recessed body (1 1) that wraps around the cathode bar (5) both on its lateral faces, lower face and upper face, leaving a central cavity (16) that crosses said closed housing (12a), from its front face towards its rear face, said central cavity (16) having a clearance to accommodate both the cathode bar (5), such as the heat-sensitive plate (10); wherein the lower wall of said recessed body (1 1) has a lower perforation (17) to accommodate a screw (15); wherein said recessed body (1 1) on its upper face an upper drain (14) as a viewfinder of the color of the heat-sensitive plate (10).  8. A system according to any of claims 1 to 6, CHARACTERIZED because the fixing means (12) is formed by a lateral housing (18), in which it has a hollowed and open lateral body (19) and a side wall detached (20), the upper face of said hollowed and open side body (19) having an upper window (14) to visualize the color on the heat-sensitive plate (10) and on the side of said upper face, locates an upper groove (21), to accommodate said removable side wall (20), which rests on the edge of the lower floor (22) of the hollowed and open side body (19), wherein said removable side wall (20) It has a side hole (17) a screw screw (15).  9. A system according to any of claims 1 to 6, CHARACTERIZED because the fixing means (12) is formed by an upper housing (23), in which it has a hollowed and open lower body (24) and a lower wall removable (25); wherein the upper face of said hollowed and open lower body (24) has an upper window (14), to visualize the color change in the surface of the heat-sensitive plate (10), and also, in one of its side walls and close to the lower edge, a lower side groove (26) is located to accommodate said removable lower wall (25) which rests on the lower lateral edge (27) of the hollowed and open lower body side wall (24), in wherein said removable bottom wall (25) has a central bottom hole (17) that houses a screw (15).  10. A system according to any of claims 7 to 9, CHARACTERIZED because in said cavity (14) it houses a translucent plate (13) which may consist of glass, translucent plastic, translucent polycarbonate or the like.  eleven . - A system according to any one of claims 1 to 6, CHARACTERIZED in that said heat-sensitive plate has a rear extension (50) and a front extension (51), which contain a first rear slot (28) and a second front slot (29) .  12. - A system according to claim 1, CHARACTERIZED in that the fixing means (12) are formed by a first rear clamp (52) that fits into the first rear slot (28) and by a second front clamp (53) which fits into the groove (29), where the first rear clamp (52) and the second front clamp (53) are formed by a plate that has the same width as the first rear groove (28) and a thickness equal to the depth of the first rear slot (28). 13. A system according to claim 12, CHARACTERIZED in that said first rear clamp (52) is formed by said folded plate, has an upper rear open side portion (38), bending to form a rear upper portion (30), bending to forming a continuous rear side portion (36), bending to form a rear floor portion (37), bending to form a lower rear open side portion (39); where from the upper rear open side portion (38) a projection emerges perpendicular to it upper rear (33) having a central upper rear perforation (54), and from the lower rear open side portion (39), a lower rear projection (32) emerges perpendicular thereto having a lower rear central perforation (44) ; wherein said first rear clamp (52) has a rear screw (46) that passes through the upper rear central perforation (54) and the lower rear central perforation (44), finishing said rear screw (46) in a rear nut (48) ; and wherein said second front clamp (53) is formed by said folded plate, which has an upper front open side portion (40), bending to form a front upper portion (31), bending to form a continuous front side portion (42 ), bending to form a front floor portion (43), bending to form a lower front open side portion (41); where from the lower front open side portion (41) a front upper projection (34) having a central perforation (54) emerges perpendicularly, and from the lower front open side portion (41), a perpendicular emergence thereof lower front projection (41) having a central perforation (55); wherein said second front clamp (53) has a front screw (47) that passes through the upper front central perforation (55) and the lower front central perforation (55), finishing said front screw (47) in a front nut (49) . 14. A system according to claim 12, CHARACTERIZED in that said first rear clamp (52) is formed by said folded plate, has an upper rear open side portion (38), bending to form a rear upper portion (30), bending to forming a continuous rear side portion (36), bending to form a rear floor portion (37), bending to form a lower rear open side portion (39); and wherein said second front clamp (53) is formed by said folded plate, which has an upper front open side portion (40), bending to form a front upper portion (31), bending to form a continuous front side portion (42 ), bending to form a front floor portion (43), bending to form a lower front open side portion (41); wherein from the upper rear open lateral portion (38) and from the upper open front lateral portion (40) a first upper perpendicular projection (56) emerges perpendicular thereto having a superior central perforation (57); wherein from the lower rear open side portion (39) and from the lower front open side portion (41), a second lower perpendicular projection (58) emerges perpendicular thereto having a superior central perforation (57); wherein said first rear clamp (52) and said second front clamp (53), have a side screw (60) that passes through the central perforation lower (59) and upper central perforation (57), finishing said lateral screw (60) in a front nut (51).  15.- A method for the early detection of short circuits and weak electrical contacts or without electrical contact in the electrodes (4) in electrolytic cells (7) of electro-obtaining or electro-refining of metals, where said detection is carried out by the change of colors of one of the elements of the system, which uses heat-sensitive pigments, CHARACTERIZED because said method comprises the following steps: (a) place in the conductive bar of each cathode bar (5) of each one electrolytic cells (4) in a cell ship of the electro-obtaining or electro-refining ship, heat-sensitive plates (10) with their corresponding fixing means, wherein each of said heat-sensitive plates (10) has in its plastic composition heat-sensitive pigments, or, formed by heat-transmitting materials, the surface of which is painted with a heat-sensitive paint film, wherein said heat-sensitive plates ( 10) they have pigments that have a "N" or normal color, for example white, and that change to a striking "A" color of high temperature, for example, within the red spectrum, for the detection of short circuits; and wherein said heat-sensitive plates (10) have pigments that have a "N" or normal color, for example white, and that change to a low temperature "B" color, for example, within the green spectrum, to determine lack of electrical contact; (b) capture the image of a plurality of heat sensitive plates (10) of a detection zone (65);  (b) transmit the image of the heat-sensitive plates (10) to a computer (63), located in an operating room;  (c) process said image to determine if any of said heat-sensitive plates (10) has changed color from "N" to "A", or "N" to "B"; Y  (d) transmit by means of a wireless transmitter (64) to a plant operator (1) the location of the detection zone (65) where the electrolytic cell (7) is associated with the heat-sensitive plates (10) that have changed of one color, 16. A method according to claim 15, CHARACTERIZED by said thermosensitive plate (10) has a color "N" when the temperature is in a range between 65 to 80 ^Q C; changes to a color "A" when the temperature rises to a value of 90 ^Q C or more; and has a color "B" when the temperature drops below 45 ^QC .