JP6660387B2 - Cell for electrowinning metal - Google Patents

Description

  The present invention relates to electrowinning of metals, in particular electrolysis devices comprising a plurality of basic cells suitable for the electrolytic production of copper and other non-ferrous metals starting from ionic solutions, and electrowinning devices in which such electrolysis devices are installed. Regarding the plant.

  Electrochemical plants for depositing non-ferrous metals, such as, for example, plants for the electrolytic extraction and purification of metals (also known as electrowinning and electrorefining plants, respectively) typically include multiple plants each including an anode and a cathode. One or more electrolyzers including the basic cells described above are used.

  In the electrolyzer for the above-mentioned plant, the anodes and cathodes are generally arranged in the electrolyzer alternately and parallel to one another. Each electrode is mechanically and electrically connected to the hanger bar, and power is supplied by bringing the respective hanger bar into contact with the bus bar. In an electrolysis apparatus, the same bus bar is shared between a plurality of electrodes of the same polarity connected in parallel to each other.

  In the case of plants for the production of non-ferrous metals such as, for example, copper, cobalt, zinc or nickel, the metal produced by the electrochemical reaction is deposited on the cathode of the respective elementary cell under the effect of current flow. I do. The precipitated product is collected by withdrawing the cathode from the associated electrolyzer, usually at regular intervals of several days. The deposition of metal on the cathode surface occurs non-uniformly, producing localized deposits, also known as dendrites or dendrites, which increase at a rate increasing under the influence of current flow, causing short-circuits. It grows towards the opposing anode until it starts. In such cases, significant damage may be caused by the elevated temperature of the anode surface corresponding to contact with the dendritic formation; in some cases, the dendritic formation may be localized on the anode surface. Joining prevents subsequent cathode withdrawal and, consequently, the entire metal extraction operation.

  The above problems associated with dendrite formation are particularly relevant in modern concept anodes made of titanium substrates such as meshes or expanded sheets provided with a coating of catalytic material. While such anodes are preferred due to their increased efficiency compared to conventional lead anodes, short-circuit conditions can often create large, irreparable damage thereto. Such a problem is addressed by a progressive anode of the type disclosed in patent application WO-2013060786 in which a catalyst-coated titanium mesh is inserted inside a shell composed of a permeable material such as a porous polymer separator or an ion exchange membrane. Also remains unresolved. Damage to the anode causes higher plant maintenance costs, loss of metal production, and additional damage related to the possibility of plant shutdown.

WO-2013060786

  Accordingly, it would be desirable to provide a form that protects the anode of the basic cell of the electrolyzer as the dendritic formation grows. It is also desirable to quickly locate and report the individual anodes of the electrolytic device where the growth of one or more dendrites constitutes a potential threat. Metal electrowinning plants detect individual anodes with dendritic formations, as they are a health hazardous environment due to high temperatures and the possibility of the presence of acid mist near the electrolyzer, and The alarming in particular allows the maintenance personnel of the plant to intervene more quickly and also has the purpose of reducing their residence time inside the electrolysis chamber.

Various aspects of the invention are set forth in the following claims.
In one aspect, the invention comprises a plurality of elementary cells, each cell including an anode and a cathode with an electrically conductive porous screen disposed therebetween, the anode having an oxygen evolution reaction. The present invention relates to an electrolysis apparatus for electrowinning metals, in which a catalyst surface is provided and the cathode is suitable for depositing metals from an electrolytic cell. The cell further includes an electrically conductive anode hanger bar electrically and mechanically connected to the anode, and an electrically conductive cathode hanger bar electrically and mechanically connected to the cathode. Each elementary cell also includes a device suitable for directly or indirectly detecting the current flowing through the corresponding anode hanger bar. The electrolyzer is also equipped with an anode bus bar electrically connected to the anode hanger bar of each cell and a cathode bus bar electrically connected to the cathode hanger bar of each cell. The electrolyzer may also include a cathode balance bar located parallel and adjacent to the anode bus bar.

  The conductive porous screen located between the anode and the cathode of the basic cell can exhibit different densities and allow the passage of electrolyte without impeding the ionic conduction between the cathode and the anode The structure is formed as follows.

  By performing electrolysis using an electrolyzer of the design described above, the dendrites that can be formed on one or more cathodes of the elementary cell are such that they reach the surface of the anode and then their growth Contacts the opposing porous screen before it stops or slows in any case. If the dendritic formation comes into contact with a porous screen, some of the metal formed in the cell may deposit directly on the screen as a coating if the screen has some electrical conductivity. Was observed. In this case, the assembly consisting of cathode, dendrite and porous screen additionally serves the function of a new cathode of the basic cell due to the electrical connection existing between these members, and furthermore Is located closer to the anode than that of In this situation, the lower ohmic drop in the electrolyte associated with the reduced gap between the new cathode and anode increases the current through the associated anode hanger bar. It has been found that the magnitude of this current increase can be used as an indicator of dendrite growth.

  In one aspect, the direct or indirect detection of the current flowing in each anode hanger bar is electrically connected to the bar itself or to the bar using a detection device capable of measuring voltage or temperature variations. Can be performed on the member that is being used.

  In one aspect, the measurement of voltage fluctuations uses an electrically conductive and possibly flexible crimp to connect the sensing device to one side of the associated anode bus bar and the other side to the cathode hanger bar. Do by doing. This configuration can provide the advantage of avoiding electrical connections fixed on the anode hanger bar and facilitating subsequent maintenance operations of the cell.

In a further aspect, the measurement of the voltage fluctuation is performed by connecting the detection device to the corresponding anode hanger bar at two points located at a fixed distance along its main axis.
In one aspect, the measurement of temperature fluctuation can be performed using a thermosensitive device, for example, a thermocouple. This measurement can be performed, for example, using a thermal device mounted on the respective anode hanger bar, preferably corresponding to its end, or on the anode bus bar corresponding to its respective point of contact with the anode hanger bar. The thermal device may be provided with a chemical resistant lining suitable to protect from and / or increase insulation therefrom.

  In another embodiment, the measurement of temperature fluctuations can be performed by using thermochromic paints that change their color as soon as the temperature exceeds a predetermined threshold. Such a coating is applied either on the anode hanger bar or on the anode bus bar corresponding to the point of contact with the anode hanger bar. This aspect allows the potentially dangerous situations defined by the growth of dendritic formations to be immediately apparent to workers working inside the electrochemical plant, and the electrolysis equipment and The advantage can be provided that one or more anodes in such an electrolysis device can be quickly identified.

  In one embodiment, each detection device can be connected to its own microprocessor configured to make a comparison between the measurement obtained by the device and a predetermined reference range; If not, the microprocessor can activate one or more alarm systems that operate sequentially or simultaneously. The microprocessor and / or alarm system can be shut down during the cathode withdrawal operation, for example, to allow for product collection. The microprocessor can be integrated with the alarm system and / or the detection device in a single unit.

  In one aspect, the microprocessor is powered by the process voltage such that use of batteries that require periodic replacement is avoided. In particular, the microprocessor can be connected directly to the anode bus bar and, if the electrolysis device is equipped with it, the cathode balance bar. If the electrolyzer does not include a cathode balance bar and it is desired to avoid fixed wiring that would interfere with plant operation, a microprocessor to monitor a particular anode hanger bar is preferably enabled. Flexible pressure contact allows connection to the anode bus bar and the hanger bar of the adjacent cathode.

  In one aspect, the microprocessor activates at least one alarm system consisting of light emitting diodes that can be connected to the optical fiber either directly or via an optical coupling device. Optical fibers, optionally lined with a polymer material, allow optical signals to be transmitted to the distal end of the respective anode hanger bar, or better still to the exterior of the electrolyzer, whereby plant operating personnel The identification is facilitated, and it is possible to quickly find the electrolyzer and the associated anode or anodes that directly or indirectly present current values outside a predetermined range of values.

  In one aspect, the porous screen can be formed of a suitably thick carbon cloth. In other embodiments, the porous screen may be comprised of a mesh or perforated sheet made of a corrosion resistant metal, such as titanium, provided with a coating that is catalytically inert to the oxygen evolution reaction. it can. In one aspect, the catalytically inert coating may be based on tin, tantalum, niobium, or titanium, for example, in the form of an oxide. In one aspect, the anode is obtained from a titanium mesh or expanded sheet coated with a catalytic material. In yet another embodiment, the catalyst-coated titanium mesh is fixed to a frame and loaded with a demister, inside a permeable separator, e.g., a skin composed of a porous sheet of a polymeric material or a cation exchange membrane. Insert

  The optimal porous screen / anode surface gap is determined by the process characteristics and the overall dimensions of the plant. In the plant used to demonstrate the invention, the best performance was obtained with a cell using an anode and cathode separated by 25 to 100 mm and a porous screen located 1 to 20 mm from the opposing anode.

  In another aspect, the invention includes an anode having a catalytic surface for an oxygen evolution reaction, a porous screen, an anode hanger bar mechanically and electrically connected to the anode, and a current flowing through the anode hanger bar. The present invention relates to an anode member for a basic cell of an electrolyzer for electrowinning metals, including devices suitable for direct or indirect detection. Apparatus suitable for detecting current directly or indirectly can be configured as described above, and in some cases, comparing the detected value to a predetermined range of values and detecting the detected value. Can be connected to a microprocessor suitable for activating one or more alarm signals if is not within a preset range. The alert signal may be acoustic, visual, electromagnetic, or of any other nature and may consist of a combination of multiple signals.

In another aspect, the invention provides:
An anode having a catalytic surface for the oxygen evolution reaction;
A cathode, arranged parallel to the anode, suitable for depositing metal from the electrolytic cell;
A porous screen arranged between the anode and the cathode;
An electrically conductive anode hanger bar integral with and electrically connected to the anode;
A device suitable for directly or indirectly detecting the current flowing through the anode hanger bar;
An anode bus bar that is electrically conductive and electrically connected to the anode hanger bar;
The present invention relates to a basic cell of an electrolysis apparatus for electrowinning a metal, comprising:

In another aspect, the invention relates to a method of obtaining copper from a solution containing cuprous and / or cupric ions, comprising electrolyzing the solution inside an electrolytic device as described above.
Several embodiments illustrating the present invention will now be described with reference to the accompanying drawings, which have the sole purpose of illustrating the mutual arrangement of the different components for such a particular embodiment of the present invention. Yes, especially the drawings are not necessarily to scale.

FIG. 1 illustrates a basic cell of an electrolyzer for electrowinning metals, which represents one aspect of the present invention. FIG. 2 illustrates a possible system for signaling dendritic formation growth in a basic cell of an electrolyzer for electrowinning metals, which represents another aspect of the present invention.

  FIG. 1 shows an anode (100) and a cathode (200) arranged parallel to the anode, suitable for depositing metal from the electrolytic cell, a porous screen arranged between the anode and the cathode. (300), suitable for directly or indirectly detecting the current flowing through the anode hanger bar (400), the cathode hanger bar (450), and the anode hanger bar (400) which are integral with and electrically connected to the anode. FIG. 3 illustrates a basic cell of an electrolysis apparatus for electrowinning metals, including a simple apparatus (500) and an electrically conductive anode busbar (600) electrically connected to an anode hanger bar (400). A device (500) suitable for directly or indirectly detecting current is connected to a microprocessor (700) configured to compare the amount detected by the device (500) to a predetermined range of values. can do. The microprocessor (700) is connected to an alarm system (800) that is activated when the detection gives a value outside the reference range.

  FIG. 2 shows a device (500) suitable for detecting current directly or indirectly, which is connected to a microprocessor (700) for comparing the detected value to a predetermined value range. The microprocessor (700) is configured to activate the alarm system (800) if the detection provides a value outside the reference range. The alarm system (800) may comprise a light emitting diode (801) that emits a light signal when activated by the microprocessor (800). The signal of the diode (801) is transmitted by an optical fiber (803) connected to the diode (800), possibly via an optical coupling system (802).

  The tip of the fiber (803) from which the optical signal is output is located at a suitable location that would be easy to identify by personnel (900) working in the plant. The above description is not intended to limit the invention, and can be used according to different embodiments without departing from the scope thereof, the scope of which is defined solely by the appended claims.

  Throughout the description and claims of this application, the term "comprising" and variations thereof such as "comprising" and "comprising" refer to the presence of other components, components, or additional process steps. It is not intended to be excluded.

  Discussion of documents, acts, materials, devices, articles and the like is included in the present specification solely for the purpose of providing a context for the present invention. Any or all of these items may have formed part of the prior art, or may be of the general general knowledge in the field relevant to the present invention prior to the priority date of the respective claims in this application. That is not suggested or specified.

Claims (16)

The basic cell of an electrolyzer for electrowinning metals, comprising:
An anode having a catalytic surface for the oxygen evolution reaction;
A cathode suitable for depositing metal from an electrolytic cell, arranged parallel to the anode;
An electrically conductive porous screen located between the anode and the cathode;
An electrically conductive anode hanger bar integral with and electrically connected to the anode;
A device suitable for directly or indirectly detecting the current flowing through the anode hanger bar;
An anode bus bar that is electrically conductive and electrically connected to the anode hanger bar;
The cell, comprising: The cell of claim 1, wherein the device suitable for detecting the current directly or indirectly comprises means for assessing a physical quantity selected between voltage and temperature. Means for assessing the physical quantity is a means for measuring the temperature using a thermochromic paint or thermal devices, cell of claim 2.   4. The cell of claim 3, wherein said thermosensitive device is a thermocouple. Said means for measuring the temperature, installed in the anode hanger on the bar corresponding to the distal end, the cell according to claim 3 or 4. It said means for measuring the temperature, is placed on the anode bus bar corresponding to the contact point between the anode hanger bar cell according to claim 3 or 4.   A microprocessor coupled to the detection device, and at least one alarm system, the microprocessor configured to compare the detected value of the current to a predetermined reference range; The cell of claim 1, wherein the system is configured to operate as soon as the detection provides a value outside the reference range. An electrically conductive cathode hanger bar integral with and electrically connected to the cathode;
・ Cathode balance bar;
The cell according to claim 7, further comprising:   9. The cell of claim 8, wherein said microprocessor power supply is provided by a process voltage.   10. The cell of claim 9, wherein the power supply is provided by connection to the anode bus bar and the cathode balance bar.   10. The cell according to claim 9, wherein the power supply is obtained by connection to the anode bus bar and pressure contact with the cathode hanger bar.   The cell according to any of claims 7 to 11, wherein the alarm system comprises a light emitting diode operated by the microprocessor.   13. The cell according to claim 12, wherein the light emitting diode is connected to an optical fiber.   An electrolyzer for primary extraction of metal from an electrolyzer, comprising a cell stack according to any one of claims 1 to 13 electrically connected to one another.   A method for obtaining copper from a solution containing cuprous and / or cupric ions, comprising a step of electrolyzing the solution inside the electrolytic device according to claim 14. An anode member for a metal electrowinning cell, the anode having at least one catalytic surface for an oxygen evolution reaction, at least one electrically conductive porous screen, mechanically and electrically connected to the anode. The anode member, comprising: an anode hanger bar, and a device suitable for directly or indirectly detecting a current flowing through the anode hanger bar.

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