JP2017524074A - Cell for electrowinning metals - Google Patents

Abstract

The invention comprises a plurality of inserted basic cells, each basic cell being equipped with a device suitable for detecting anomalies in the distribution of current to the respective anode, for electrowinning non-ferrous metals. The present invention relates to an electrolysis apparatus. [Selection] Figure 1

Description

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

  Electrochemical plants for depositing non-ferrous metals, such as, for example, a plant for electrolytic extraction and purification of metals (also known as electrowinning and electrorefining plants, respectively) typically include multiple anodes and cathodes, respectively. One or more electrolyzers including the following basic cells are used.

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

  In the case of a plant for producing non-ferrous metals such as copper, cobalt, zinc or nickel, the metal produced by the electrochemical reaction is deposited on the cathode of each basic cell under the action of current passage. To do. The precipitated product is collected by extracting the cathode from the relevant electrolyzer, usually at regular intervals of several days. Metal deposition on the cathode surface occurs non-uniformly, producing local deposits, also known as dendrites or dendrites, which increase at a rate under the influence of current flow and short circuits occur. Grow towards the opposing anode until it begins. In such a case, significant damage can be caused by an increase in temperature of the anode surface corresponding to contact with the dendritic formation; in some cases, the dendritic formation is locally on the anode surface. Bonding prevents subsequent withdrawal of the cathode and consequently the entire metal extraction operation.

  The above-mentioned problems associated with the formation of dendrites are particularly relevant in modern concept anodes made with titanium substrates such as mesh or expanded sheets provided with a coating of catalyst material. Such anodes are preferred because of their increased efficiency compared to conventional lead anodes, but short-circuit conditions can often create large, irreparable damage to them. Such a problem is an advanced anode of the type disclosed in the patent application WO-2013060786 in which a catalyst coated titanium mesh is inserted inside a skin composed of a permeable material such as a porous polymer separator or an ion exchange membrane. Remains unresolved. Damage to the anode causes additional plant maintenance costs, loss of metal production, and additional damage related to the potential for the plant to be shut down.

WO-2013060786

  Accordingly, it would be desirable to provide a form that protects the anode of the base cell of the electrolyzer when the dendritic growth is grown. It is also desirable to quickly locate and report the individual anodes of the electrolyzer where growth of one or more dendriforms constitutes a potential threat. Since the metal electrowinning plant is a health-harmful environment due to the high temperature and potential for acid mist in the vicinity of the electrolyzer, it detects individual anodes on which dendrites have formed, and Alerting in particular has the purpose of allowing plant maintenance personnel to intervene more quickly and reducing their residence time inside the electrolytic chamber.

Various aspects of the invention are set out in the accompanying claims.
In one form, the present invention is comprised of a plurality of basic cells, each cell including an anode and a cathode with an electrically conductive porous screen disposed therebetween, the anode having an oxygen generating reaction. The present invention relates to an electrolyzer for electrowinning metal, wherein a catalyst surface is provided and the cathode is suitable for depositing metal 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 basic cell also includes a device suitable for directly or indirectly detecting the current through the corresponding anode hanger bar. The electrolyzer is also equipped with an anode bus bar that is electrically connected to the anode hanger bar of each cell, and a cathode bus bar that is electrically connected to the cathode hanger bar of each cell. The electrolyzer can also include a cathode balance bar disposed in parallel and in close proximity to the anode bus bar.

  Conductive porous screens placed between the anode and cathode of the basic cell can exhibit different densities and allow electrolyte to pass through without interfering with ionic conduction between the cathode and anode. It is a structure formed as described above.

  By performing electrolysis using the electrolyzer of the design described above, dendrites that can be formed on one or more cathodes of the basic cell are grown after they reach the surface of the anode. Contacts the opposing porous screen before it stops or in any case slows down. When the dendriform is in contact with the porous screen, if the screen has some electrical conductivity, some of the metal produced in the cell may be deposited directly on the screen as a coating. Observed. In this case, the assembly composed of the cathode, dendrite and porous screen additionally serves as the new cathode of the basic cell because of the electrical connection that exists between these members, and further to the original. Placed closer to the anode than the one. In this situation, the lower ohmic drop in the electrolyte associated with the reduced gap between the new cathode and anode increases the current flowing through the associated anode hanger bar. It has been found that this degree of current increase can be used as an indication of dendrite growth.

  In one aspect, direct or indirect detection of the current flowing in each anode hanger bar is electrically connected to the bar itself or to it using a detection device that can measure voltage or temperature variations. Can be carried out on the member.

  In one aspect, the measurement of voltage fluctuations uses electrically conductive and possibly flexible crimps to connect the sensing device, one side to the associated anode bus bar and the other side to the cathode hanger bar. By doing. This configuration can provide the advantage of avoiding electrical connections that are 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 constant distance along its main axis.
In one aspect, temperature fluctuations can be measured using a thermal device, such as a thermocouple. This measurement can be performed, for example, using a heat sensitive device mounted on the anode hanger bar, preferably on the respective anode hanger bar corresponding to its end, or on the anode bus bar corresponding to the respective contact point with the anode hanger bar. The thermal device may be provided with a chemical resistant lining suitable for protecting from the ambient atmosphere and / or increasing thermal insulation therefrom.

  In another aspect, temperature fluctuations can be measured by using thermochromic paints that change their color as soon as the temperature exceeds a predetermined threshold. Such paint 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 quickly reveals potentially dangerous situations defined by dendritic growth to workers working inside the electrochemical plant, and the electrolyzers in which these situations occur and The advantage may be that one or more anodes in such an electrolyzer can be quickly identified.

  In one aspect, each detection device can be connected to its own microprocessor that is configured to perform a comparison between the measured value obtained by the device and a predetermined reference range; If not within the reference range, 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 extraction operation, for example considering product collection. The microprocessor can be integrated in a single unit with the alarm system and / or the detection device.

  In one aspect, the microprocessor is driven by a process voltage so that the use of batteries that require periodic replacement is avoided. In particular, the microprocessor can be connected directly to the anode bus bar and to the cathode balance bar if the electrolyzer is equipped with it. 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 for monitoring a particular anode hanger bar is preferably acceptable. It can be connected to the anode bus bar and the adjacent cathode hanger bar by flexible pressure welding.

  In one aspect, the microprocessor activates at least one alarm system comprised of light emitting diodes that can be connected directly to the optical fiber or via an optical coupling device. An optical fiber, optionally lined with a polymer material, allows optical signals to be transmitted to the end portion of each anode hanger bar, or better, outside the electrolyzer, which allows plant operators to Its 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 carbon cloth of suitable thickness. In other embodiments, the porous screen may be composed of a mesh or perforated sheet made of a corrosion resistant metal, such as titanium, that is 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 embodiment, the anode is obtained from a titanium mesh or expanded sheet coated with a catalytic material. In yet another embodiment, a catalyst-coated titanium mesh is secured to the frame and is mounted on a permeable separator, such as a porous sheet of polymer material or a cation exchange membrane, mounted on a demister. Insert into.

  The optimum 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 present invention, the best performance was obtained with a cell using an anode and cathode spaced 25-100 mm apart and a porous screen placed 1-20 mm away from the opposing anode.

  In another form, the present invention provides 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 invention relates to an anode member for a basic cell of an electrolysis device for electrowinning metals, including a device suitable for direct or indirect detection. A suitable device for directly or indirectly detecting the current can be configured as described above, and in some cases, the detected value is compared to a predetermined range of values and the detected value is Can be connected to a suitable microprocessor to activate one or more alarm signals when the is not within the preset range. The alarm signal may be acoustic, visual, electromagnetic, or of any other nature, and may consist of a combination of multiple signals.

In another form, the present invention provides:
An anode having a catalytic surface for oxygen evolution reaction;
A cathode suitable for depositing metal from an electrolytic cell, arranged parallel to the anode;
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.

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 the electrolyzer 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 members for such specific embodiments of the present invention. In particular, the drawings are not necessarily to scale.

FIG. 1 illustrates a basic cell of an electrolysis apparatus for electrowinning a metal that represents one embodiment of the present invention. FIG. 2 illustrates a possible system for signaling dendritic growth in a basic cell of an electrolyzer for electrowinning metals representing another aspect of the present invention.

  FIG. 1 shows an anode (100), a cathode (200) suitable for depositing metal from an electrolytic cell, arranged parallel to the anode, and a porous screen arranged between the anode and 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) that are integrated with and electrically connected to the anode. FIG. 1 illustrates a basic cell of an electrolyzer for electrowinning metals, including an apparatus (500), an electrically conductive anode bus bar (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) with 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 an apparatus (500) suitable for directly or indirectly detecting current, connected to a microprocessor (700) for comparing the detected value with a predetermined range of values. The microprocessor (700) is configured to activate the alarm system (800) when the detection gives a value outside the reference range. The alarm system (800) may consist of a light emitting diode (801) that emits an optical 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 then placed at a suitable location that may be easily identified by the staff (900) working in the plant. The above description is not intended to limit the invention and can be used in accordance with different embodiments without departing from the scope thereof, the scope of which is defined solely by the appended claims.

  Throughout the specification and claims of this application, the term “comprising” and variations thereof such as “comprising” and “including” shall imply the presence of other components, parts, or additional process steps. It is not intended to be excluded.

  Discussion of documents, acts, materials, devices, articles, etc. is included herein solely for the purpose of providing a content for the invention. Any or all of these matters form part of the basis of the prior art or are common general knowledge in the field relevant to the present invention prior to the priority date of each claim of this application. It is neither suggested nor stated.

Claims (16)

A basic cell of an electrolysis device for the electrowinning of metals:
An anode having a catalytic surface for oxygen evolution reaction;
A cathode suitable for depositing metal from an electrolytic cell, arranged parallel to the anode;
An electrically conductive porous screen disposed between the anode and the cathode;
An electrically conductive anode hanger bar integral with and electrically connected to the anode;
An apparatus 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;
Including the cell.   The cell of claim 1, wherein detecting the current directly or indirectly includes assessing a physical quantity selected between voltage and temperature.   The cell according to claim 2, wherein assessing the physical quantity is measuring a temperature using a thermochromic paint or a thermal device.   The cell of claim 3, wherein the thermal device is a thermocouple.   The cell according to claim 3 or 4, wherein the temperature measurement is performed on the anode hanger bar in the vicinity of an electrical connection with the anode bus bar.   The cell according to claim 3 or 4, wherein the temperature measurement is performed on the anode bus bar in the vicinity of the anode hanger bar.   A microprocessor connected to the detection device; and at least one alarm system, wherein the microprocessor is configured to compare the detected value of the current with 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 of claim 7 further comprising:   9. The cell of claim 8, wherein the microprocessor power supply is provided by a process voltage.   The cell according to claim 9, wherein the power supply is obtained by connection to the anode bus bar and the cathode balance bar.   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.   12. A cell according to any of claims 7 to 11, wherein the alarm system comprises a light emitting diode activated by the microprocessor.   The cell of claim 12, wherein the light emitting diode is connected to an optical fiber.   An electrolysis apparatus for primary extraction of metal from an electrolytic cell, comprising the cell laminate according to any one of claims 1 to 13, which are electrically connected to each other.   The method to obtain copper from the solution containing 1st copper and / or 2nd copper ion including the process of electrolyzing a solution inside the electrolytic device of Claim 14.   An anode member for a metal electrowinning cell comprising an anode having at least one catalytic surface for an oxygen evolution reaction, at least one porous screen, and an anode hanger mechanically and electrically connected to said anode The anode member comprising a bar and a device suitable for directly or indirectly detecting the current flowing through the anode hanger bar.

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