WO2020073143A1 - Sistema para inyectar corriente alterna en celdas electrolíticas, en grupos consecutivos de electrodos - Google Patents
Sistema para inyectar corriente alterna en celdas electrolíticas, en grupos consecutivos de electrodos Download PDFInfo
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- WO2020073143A1 WO2020073143A1 PCT/CL2019/050097 CL2019050097W WO2020073143A1 WO 2020073143 A1 WO2020073143 A1 WO 2020073143A1 CL 2019050097 W CL2019050097 W CL 2019050097W WO 2020073143 A1 WO2020073143 A1 WO 2020073143A1
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- alternating current
- electrodes
- cell
- current
- electrode
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C1/00—Electrolytic production, recovery or refining of metals by electrolysis of solutions
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C7/00—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells
- C25C7/06—Operating or servicing
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Definitions
- Electrolytic copper is produced industrially through electrolytic processes that are: (i) the final stage of processing of oxidized minerals and secondary sulphides, whose transformation into metallic copper, occurs through the process of electrowinning (EW, electrowinning), and (ii) the final stage of primary sulfide mineral processing, through the electro refining (ER) process.
- Electrolytic copper is produced on metal cathodes, which is the main format in which copper is sold in the world.
- Electrolytic processes occur inside electrolytic cells, in which the electrodes (anodes and cathodes) are inserted. It is possible to define the concept of "elemental electrolytic cell", as the set made up of an anode surface facing a cathodic surface, electrically connected through the electrolyte contained between them.
- industrial electrolytic cells are made up of multiple elementary electrolytic cells, in which the anodes are connected to a common bar, through which the positive pole of the direct current source is connected, and the cathodes to another common bar, through which the negative pole of the direct current source is connected.
- the cells are grouped together and electrically connected in series to a direct current electrical source, usually a rectifying transformer, which produces the direct current necessary for the copper dissolved in the electrolyte to deposit in the cathodes.
- the direct current enters the electrolyte from the anodes, through a process of oxidation of water molecules, of which the electrolyte is formed, by which gaseous oxygen is generated, which escapes to the surface, and protons (H + ) they act as ionic electrical carriers; causing in turn and simultaneously, that the copper is deposited on the cathodes, through a process of reduction, at a rate that is determined by the intensity of the direct current.
- the electrolyte that circulates inside the electrowinning cells is an ionic solution composed of: water, sulfuric acid, in a concentration of around 180 [gr / lt] and copper, in a concentration of 30 to 50 [gr / lt] for the EW process;
- the incoming electrolyte is rich electrolyte and the outgoing electrolyte of the cells is poor electrolyte, since the electrowinning process decreases the copper concentration.
- the electrolyte that circulates inside the electro-refining cells has slightly higher concentrations, between 40 and 60 [gr / lt] and, in this case, the electrolyte leaving the cells has a higher concentration than the concentration of the incoming electrolyte Because the deposition process is a cascade of the dissolution process, therefore, the deposition rate (mass / unit time) of copper on the cathodes must be less than the dissolution rate of the anodes. To control the copper concentration, the electro-refining plants have groups of auxiliary electrowinning cells.
- the anodes for industrial electrowinning processes are, for the most part, lead sheets with a copper bar soldered on the upper edge, which operates as a mechanical support, in which one of its ends operates as a connection terminal to the bar inter-cell and, in which the other, is a simple mechanical support (inert terminal).
- a coating of lead dioxide is formed, which catalyzes the oxidation reaction of the water.
- Lead anodes have thicknesses between 6 and 9 [mm] of lead, for new anodes, which decreases over the life of the anodes, since the oxidation process of the water is chemically aggressive, due to the generation of protons (high local pH), as mechanically aggressive, due to the permanent formation of gaseous oxygen bubbles. Due to this, it is observed that lead anodes are not dimensionally stable. To solve this, technologies have been developed that tend to provide dimensionally stable anodes (DSA), based on sheets or rectangular meshes of titanium, covered by noble metal oxides, which together with an effect of reducing the anode over potential, generate an interesting alternative to replace lead anodes. The rectangular mesh structure gives the process an improvement in the circulation of the electrolyte.
- DSA dimensionally stable anodes
- the anodes are shaped as rectangular plates of impure copper, in thicknesses of the order of 40 [mm], in newly planted anodes, and which, as a result of the oxidation process, dissolve and supply the copper to the electrolyte, to then deposit on the cathode, while a part of the impurities precipitate at the bottom of the cell, forming the anode mud.
- the cathodes for the electro-obtaining and electro-refining processes can be formed as permanent cathodes or as initial sheets.
- the permanent cathodes are made up of stainless steel sheets with a copper bar welded to its upper edge, which acts as a mechanical support and connection terminal to the inter-cell bar, which are inserted without copper and, later, after a deposit period that varies between four and seven days, depending on the applied DC density, they are removed with metallic copper adhered on both sides;
- the initial copper sheets which are the product of a previous process that produces them for this purpose, are seeded in the cell. On these initial sheets, copper is then deposited, which is harvested after a certain time.
- Protons (H +) agglomerate around the cathodic surface because they require an energy higher than the energy required by copper ions to reduce.
- a similar phenomenon of large proton agglomeration occurs in the vicinity of the anode surface, where the anodes are generated from the oxidation of water.
- the agglomerations of electric charges generate electric fields and potentials (and vice versa), whose intensities and values are determined by strict mathematical relationships (Maxwell's laws), such that an agglomeration of ions (protons and other ionic species) It will generate a high electric field which, in turn, will cause a high difference in electric potential.
- the overpotentials are added to the thermodynamic potential to determine the energy consumption of the electrowinning and electrorefining processes.
- the agglomeration of protons and other ionic species, at the cathodic interface largely determines the cathodic over-potential, as well as a high electric field, which, in turn, determines "the climate” in which it occurs.
- the reduction of copper ions a phenomenon that, instead of occurring through charge transfer, in this climate tends to occur through dielectric breakdown.
- the direct current flows from the face of the anodes and then, through the electrolyte to the face of the cathodes, as a result of the electrical source being firmly connected at the terminals of the anodes, at its positive pole, and at the cathodes, at its negative pole, so that the electric field lines and the direct current circulate, from each electrode to the consecutive electrodes, exclusively (figure 1).
- the propagation rate of the error will not be even, because there are two extreme electrodes in which the source is connected and, from them, to the center of the group.
- the graph of the alternating current intensity will present a shape similar to a hyperbolic or similar cosine function (figure 3.1 and 3.2).
- the current that circulates from the anode surfaces to the cathodic ones is determined by the phenomenon modeled and studied by electrochemical kinetics and which can be expressed by means of graphs in the Vl plane (voltage-current plane). Accordingly, the overpotentials in the vicinity of the surface of the electrodes are an increasing function of the intensity of direct current, so if more current flows through a given area of the electrode surface, then the potential override increases.
- the voltages In the context in which the electrodes are connected in parallel, the voltages must be equal, so that the existence of overpotentials acts as a control mechanism for the intensity of the direct current.
- the distribution of direct current on the electrode surfaces is determined by a current divider with resistive impedances (objects in the V-l plane).
- the current distribution between the electrodes will be even; therefore, the irregularity of the current distribution between electrodes is mainly determined by the aforementioned electrolyte conditions.
- the technical problem to be solved consists of how to implement the superposition of alternating current, of high intensity and controlled, with a frequency greater than 5 [KHz], on the direct current, which circulates from the anode surfaces to the cathodic surfaces, in electrolytic cells that contain multiple anodes and intercalated cathodes, both for electro-obtaining processes and for electro-refining processes of copper and other metals, mitigating the variability effect of alternating current on the surfaces of the electrodes, product of circulation by the alternative paths and mitigating the spread of the variability of the intensity of the alternating current, product of local process defects, which is evidenced by connecting an alternating current source at the end electrodes of the cell, producing a current distribution alternates in the electrodes that presents a high variability, similar to the graph or 1 in figure 3. THE INVENTION
- the invention object of this invention patent application, proposes to solve the technical problem, "bringing the source terminals closer to the intermediate electrodes", so that the intermediate electrodes also have an alternating current intensity close to the intensity of the source, which is accomplished by installing multiple alternating current sources connected to intermediate electrodes. In this way, the alternating current is forced, each certain reduced number of electrodes, to flow in a high proportion of its maximum intensity, through their surfaces (figure 4), obtaining a distribution of alternating current intensities in the electrodes, similar to that shown in graph 3 or 4 of figure 3.
- the invention constitutes, then, as a system to superimpose alternating current, of high and controlled intensity and with a frequency greater than 5 [KHz], on the direct current that circulates from the anode surfaces to the cathodic surfaces, in electrolytic cells that contain multiple intercalated anodes and cathodes, for electro-obtaining or electro-refining processes of copper and other metals, characterized by supplying alternating current, in consecutive groups of electrodes, each of which is, in turn, made up of a reduced number of consecutive electrodes, so that the supplied alternating current flows from the surface of the first electrode to the surface of the last electrode in each group and, from the surfaces of each electrode to the surface of the consecutive electrode, through the electrolyte contained between the electrodes of each group, and in which the groups of electrodes, include all the cathodes of the cell; While, simultaneously, the direct current circulates in parallel, from the anode surfaces to the cathodic surfaces, and through the electrolyte contained between the electrodes, and in which the number of electrodes in
- Alternating current sources can easily be implemented as inverters that generate current of the appropriate frequency for the process.
- An important characteristic, which must be considered in the design of these sources, is that, although the current to be injected into the cell groups is relatively high (over 200 [Arms]), the active power required by the process is practically null, since the current circulates through the capacitors of the interfaces) and through the electrolyte, which has a very high electrical conductivity, and must then supply only the power of the losses in: the elements of the source, in the conductors and in the connection elements.
- the sources consisting of: an AC / DC converter or a DC / DC converter, a low current inverter and a transformer with a turn in the secondary winding, will turn out to be very robust and low cost, being easily adaptable to operate in the environmental and geometric conditions, which characterize industrial electrolytic processes.
- Electric transformers can be implemented with flat spiral primary and secondary windings, as well as can be implemented with a tubular secondary winding (a spiral) and a primary winding, inserted inside. In both cases, the implementations of the transformers will comply with being robust, with minimal geometry and very low cost (Figure 5).
- cathode mobilization operations are at least twice that of anode mobilization operations. For this reason, and to facilitate electrode mobilization operations (avoiding short circuits and mechanical risk, etc.), the cathodes have a bar or an exposed connection implement (aza, ear, etc.). The fact that all the cathodes are more exposed than the anodes, allows to visualize possible alternatives for the connection and for the eventual installation of the removable sources, based on electrical transformers, arranged on the cathodes of the cell (figure 6).
- the main irregularity has to do with the fact that the electrodes (anodes and cathodes) are inserted at horizontal distances, which are not perfectly regular, since the rests that determine their position (the “capping board”), suffer wear due to use and because they must have an obtuse insertion angle (greater than 90 °).
- Another cause of irregularity, of lower incidence is the irregularity of the relative height of the electrodes, which can be caused by different levels of wear of the capping boards or because the electrode support bar is bent or has an altered geometry, product of a fall or other mechanical impact.
- the end of the horizontal bar can be used at the opposite end where the direct current connection is made (inert terminal), which is not exposed to current circulation continuous, which is an available resource that could be used to make the connection of the alternating current sources (figure 8).
- the sources with an electrical transformer near the capping board and connect them to the inert terminal of the anodes which is possible, given that the frequency transformers over 5 [KHz] they can be implemented in volume and small geometry.
- the frequency transformers over 5 [KHz] they can be implemented in volume and small geometry.
- Another possibility is to include the alternating current source as part of the electrode, particularly at the anode, attached to the inert end of the bar.
- connection system must take care of the irregularity of the position of the electrodes, by means of a connection system similar to the sowing and harvesting device ( Figures 6 and 7).
- elements are installed on the cells, such as: hoods, meshes, blankets, etc., to reduce heat loss or to mitigate the emission of acid mist, which are easily adaptable to coexist with the invention.
- alternating current sources when connected in consecutive groups of consecutive electrodes, result in a series connection of sources, however, it seems appropriate to connect consecutive sources with electrical 180 ° lags, since, in this way , the sum of the voltages of the consecutive sources tends to zero, avoiding the circulation of leakage alternating current between the terminals of source pairs. It also seems appropriate to install an even number of sources and thus the sum of the voltages of the consecutive sources in a cell will be null at all times. It is also possible to carry out implementations with various lags, but this will cause leakage currents to circulate between the terminals of different sources.
- FIGURE 1 Plan view of the appearance of the field lines in a group of consecutive electrodes that contains three anodes and two cathodes and that is fed with direct current, from the anodes to the cathodes.
- the electric field lines connect each electrode with both electrodes that are consecutive, exclusively.
- FIGURE 2 Plan view of the appearance of the field lines in a group of consecutive electrodes that contains three anodes and two cathodes and that is supplied with direct current, from the anodes to the cathodes and with alternating current, from the first anode to the last anode of the group.
- Electric field lines are observed that connect each electrode with each and every other electrode in the group, which implies that the alternating current also circulates between the interior surface of the cell and the edges of the electrodes.
- FIGURE 3 Graph of current intensity in the typical EW cell electrodes of 60 cathodes and 61 anodes, for the case in which the invention does not apply (1), for the case in which the invention is applied in groups of shaped electrodes by 10 cathodes and 1 1 anodes (2), for the case in which the invention is applied in groups of electrodes made up of 5 cathodes and 6 anodes (3) and case in which the invention is applied in groups of electrodes made up of 2 cathodes and 3 anodes (4).
- the current distribution shows great irregularity and, in cases 3 and 4, the distribution regularity improves remarkably, as a result of the application of the invention. It is also observed that the regularity of the current distribution in the electrodes improves when the number of electrodes in the groups is reduced.
- FIGURE 4 Scheme of the invention in an electrolytic cell, with a view of the cross section of the cell (A) and in view of the longitudinal section of the cell (B), showing: direct current source (5), alternating current source (6) and anodes (7), and cathodes (8).
- FIGURE 5 Scheme of the invention, seen in longitudinal section, of the cell in which they are observed: an alternating current source (6) for each group of electrodes (B), an alternating current source (6) for two or more groups of electrodes (C) and an alternating current source (6) for all consecutive groups of electrodes in cell (D).
- FIGURE 6 Electric transformers with air core, implemented in a cylindrical structure with a secondary turn and a primary winding with multiple turns, arranged inside with connection terminals perpendicular to the cylindrical body (9) and with connection terminals parallel to the cylindrical body ( 10).
- FIGURE 7 Diagram of installation, on the electrodes, of removable alternating current sources with a cylindrical electrical transformer (10) and a bolt for connection, with the following elements: cylindrical electrical transformer (10); elastic element (12), which maintains contact pressure, even when there is a horizontal irregularity in the position of the electrode; position stop (13) for a horizontal irregularity of the electrode; handle or handle for the manipulation of the bolt (position closed) (14); latch handle or handle (open position) (15); and horizontal rod or tube of the electrode (cathode (8)) and anode (7).
- FIGURE 8 Detail of aza and bolt installation for connection: aza or handle for manipulation of the bolt (closed position) (14); latch handle or handle (open position) (15); elastic element that maintains contact pressure (12); connection terminal to the electrode (16); position stop for a horizontal irregularity (13) of the electrode; horizontal bar or tube of electrode (cathode) (8); conductive plate (11) with flexible conductive plate (17).
- FIGURE 9 Proposal for the implementation of the invention for electrowinning plants, with sources and / or conductors arranged on the cells, tilted on inert anode terminals (7) and connected to cathodes (8).
- FIGURE 10 Installation diagram of fixed alternating current sources with a cylindrical electrical transformer and elastic connection clips, under the underside of the electrode bars.
- FIGURE 11 Isometric view of the installation of fixed alternating current sources with a cylindrical electrical transformer and elastic connection clips, under the underside of the electrode bars. The following items are displayed: transformer cylindrical electrical (9), electrode connection terminal (21), elastic clips (20), inert anode terminal (7), triangular inter-cell bar (19) and cell wall (22).
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Abstract
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Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
BR112021006990-9A BR112021006990A2 (pt) | 2018-10-11 | 2019-10-10 | sistema para injetar corrente alternada em células eletrolíticas, em grupos consecutivos de eletrodos |
PE2021000492A PE20211406A1 (es) | 2018-10-11 | 2019-10-10 | Sistema para inyectar corriente alterna en celdas electroliticas, en grupos consecutivos de electrodos |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CL2901-2018 | 2018-10-11 | ||
CL2018002901A CL2018002901A1 (es) | 2018-10-11 | 2018-10-11 | Un sistema para inyectar corriente alterna en celdas electrolíticas que contienen múltiples ánodos y catados intercalados, para procesos de electro obtención o electro refinación de cobre y otros metales; el cual provee la corriente alterna, en grupos consecutivos de electrodos. |
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WO2020073143A1 true WO2020073143A1 (es) | 2020-04-16 |
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PCT/CL2019/050097 WO2020073143A1 (es) | 2018-10-11 | 2019-10-10 | Sistema para inyectar corriente alterna en celdas electrolíticas, en grupos consecutivos de electrodos |
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BR (1) | BR112021006990A2 (es) |
CL (1) | CL2018002901A1 (es) |
PE (1) | PE20211406A1 (es) |
WO (1) | WO2020073143A1 (es) |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP3072993A2 (en) * | 2013-11-19 | 2016-09-28 | Hecker Electrónica Potencia Y Procesos S.A. | Method of superimposing alternating current on direct current for methods for the electrowinning or electrorefining of copper or other products, in which the alternating current source is connected between two consecutive cells of the electrolytic cell group using an inductor for injecting alternating current and a capacitor for closing the electric circuit |
CL2018000114A1 (es) * | 2018-01-15 | 2018-05-11 | Robledo Juan Pablo Bustos | Sistema para inyectar corriente alterna en los electrodos extremos de celdas electrolíticas, de manera que la corriente alterna circula en serie desde el primer hasta el ultimo electrodo y desde un el electrodo mientras la corriente continua circula en paralelo desde los ánodos a los cátodos |
-
2018
- 2018-10-11 CL CL2018002901A patent/CL2018002901A1/es unknown
-
2019
- 2019-10-10 PE PE2021000492A patent/PE20211406A1/es unknown
- 2019-10-10 BR BR112021006990-9A patent/BR112021006990A2/pt unknown
- 2019-10-10 WO PCT/CL2019/050097 patent/WO2020073143A1/es active Application Filing
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP3072993A2 (en) * | 2013-11-19 | 2016-09-28 | Hecker Electrónica Potencia Y Procesos S.A. | Method of superimposing alternating current on direct current for methods for the electrowinning or electrorefining of copper or other products, in which the alternating current source is connected between two consecutive cells of the electrolytic cell group using an inductor for injecting alternating current and a capacitor for closing the electric circuit |
CL2018000114A1 (es) * | 2018-01-15 | 2018-05-11 | Robledo Juan Pablo Bustos | Sistema para inyectar corriente alterna en los electrodos extremos de celdas electrolíticas, de manera que la corriente alterna circula en serie desde el primer hasta el ultimo electrodo y desde un el electrodo mientras la corriente continua circula en paralelo desde los ánodos a los cátodos |
Also Published As
Publication number | Publication date |
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BR112021006990A2 (pt) | 2021-07-20 |
PE20211406A1 (es) | 2021-08-02 |
CL2018002901A1 (es) | 2019-02-01 |
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