WO2007124605A1 - Cellule électrolytique comprenant des moyens permettant de déloger des dépôts électrolytiques d'une électrode - Google Patents

Cellule électrolytique comprenant des moyens permettant de déloger des dépôts électrolytiques d'une électrode Download PDF

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Publication number
WO2007124605A1
WO2007124605A1 PCT/CA2007/000768 CA2007000768W WO2007124605A1 WO 2007124605 A1 WO2007124605 A1 WO 2007124605A1 CA 2007000768 W CA2007000768 W CA 2007000768W WO 2007124605 A1 WO2007124605 A1 WO 2007124605A1
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WIPO (PCT)
Prior art keywords
cathode
electrolytic cell
stream
electrode
rotatable
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PCT/CA2007/000768
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English (en)
Inventor
Yves Michel Henuset
Benoît MOREAU
Bruno Desmarais
Frédéric BITON
Danielle Miousse
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Global Ionix
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Publication of WO2007124605A1 publication Critical patent/WO2007124605A1/fr

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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
    • C25C7/02—Electrodes; Connections thereof
    • 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
    • C25C7/08—Separating of deposited metals from the cathode

Definitions

  • the present invention relates to the field of electrolysis, and in particular to a method and apparatus for the recovery of metals from solution by electrowinning.
  • An object of the invention is to permit the recovery of metals from solutions that cannot be conveniently recovered as powders as well as to provide an alternative technique useful for other metals.
  • an electrolytic cell for the recovery of metal from a solution, comprising a cell cavity for receiving the solution; a rotatable electrode in the cavity having a single electrode face or a pair of opposite electrode faces; counter electrode portions in spaced and opposing relationship with the respective single or opposite electrode faces of the rotatable electrode to supply a current through solution in the cavity to permit extraction of the material by electrochemical reaction; and at least one nozzle for directing a stream of flowable material under pressure onto the cathode to dislodge metal extracted from the solution by an electrochemical reaction.
  • an electrolytic cell for the recovery of metal from a solution, the cell comprising a cell cavity for receiving the solution; a rotatable cathode located within the cavity; at least one counter-electrode in spaced relationship with the rotatable cathode; and at least one nozzle for directing a stream of flowable material under pressure onto the cathode to dislodge metal extracted from the solution by an electrochemical reaction.
  • an electrolytic cell for the recovery of metal from a solution, the cell comprising: a cell cavity for receiving the solution; at least one rotatable electrode adapted to be disposed within the cavity, the rotatable electrode having at least one face; at least one counter-electrode in spaced relationship with the rotatable electrode; and at least one nozzle adapted to direct a stream of flowable material under a pressure of at least 250 psi onto at least one of the electrodes to dislodge metal extracted from the solution by an electrochemical reaction.
  • an electrolytic cell for the recovery of material from a solution, comprising a cell cavity for containing the solution; a rotatable electrode in the cavity having a pair of opposite electrode faces; counter electrode portions in spaced and opposing relationship with the respective opposite electrode faces of the rotatable electrode to supply a current through solution in the cavity to permit extraction of the material by electrochemical reaction; and at least one nozzle for directing a stream of flowable material under pressure onto at least one of the opposite electrode faces of the rotatable electrode so as to dislodge metal extracted from the solution by an electrochemical reaction.
  • the at least one nozzle is adapted to direct the stream onto the surface defined by at least one of the opposite electrode faces of the rotatable electrode in a direction that is intermediate between a direction normal to the surface of the rotatable electrode and a direction tangential to the surface of the rotatable electrode.
  • a method of recovering metal from a solution comprising placing the solution in a cell cavity containing a rotating cathode; depositing the metal on the surface of the rotatable electrode by electrochemical reaction; and directing high pressure flowable material onto the surface of the cathode to dislodge metal extracted from the solution.
  • a method of dislodging a metal foil deposited on an electrode having a generally cylindrical shape comprises directing at least one stream of a flowable material onto the surface of the electrode in a direction that is intermediate between a direction normal to the surface of the electrode and a direction tangential to the surface of the electrode.
  • the at least one stream is applied at a pressure of at least 250 psi.
  • a method of dislodging a metal foil deposited on an electrode having a generally cylindrical shape comprises directing at least one stream of a flowable material onto the surface of the electrode in a direction that is about in the middle between a direction normal to the surface of the electrode and a direction tangential to the surface of the electrode.
  • the flowable material directed under pressure can be water, air or the electrolyte solution itself, or it can be a solid material, such as metallic, ceramic or plastic pellets, flakes or powders. Alternatively, it can be an organic or inorganic liquid, with and/or without soluble and/or insoluble matter, such as salts, plastic and/or ceramic media. These can be entrained in a fluid, such as air or water. Alternatively, the flowable material can be directed at the cathode that is immersed or not in the electrolyte solution.
  • the rotatable electrode can be a cathode, which is in the form of a single or double-faced cylinder having either internal and/or external faces available for deposition.
  • the second electrode portions form part of a common anode and are defined by the outwardly facing surfaces of an annular channel receiving the cylindrical cathode. Alternatively, the second electrode portions could be separate elements facing the opposite face of the cathode when needed.
  • the cathode can be a double-faced cylindrical cathode, and nozzles of flowable material can be directed at its inner and outer faces.
  • the cathode can be a double-faced cathode, and at least one nozzle is provided to remove deposited metal from the internal and external faces of the double-face cathode. At least one nozzle can be located inside the rotatable cathode.
  • the rotatable electrode can be a cylinder, as noted above, but for example, the rotatable electrode, could also have a grating or mesh structure, or could be porous so as to have a three-dimensional sponge structure.
  • the counter-electrode can be placed in such a way that both electrode surfaces (anode and cathode) face one another in a parallel fashion.
  • the distance between both inner and outer faces can be equal in order to achieve symmetry in the assembly, thus providing similar electrochemical conditions for both surfaces of the double-face rotatable electrode.
  • the distance between each pair of electrode and counter-electrode can be adjusted in such a way that a different tangential speed is obtained.
  • electrochemical properties that link this latter parameter to the reactor efficiency are respected.
  • the counter electrode can include openings and/or spaces to allow the flowable material to pass through as it is directed onto the rotatable cathode.
  • the electrochemical conditions can be set in such a manner that the metal is deposited on either one or both sides of the rotatable cathode as a foil or powder, and then the deposit is removed from the cathode with the aid of high-pressure fluid nozzles.
  • Metals can be deposited as powders, flakes or foils. Unlike powders and flakes, foils are deposited as a continuous film on the cathode and are not easily removed by conventional methods. It has been found that the use of high-pressure fluid nozzles can overcome the problem of extracting thin foil of deposits over the rotatable cathode. This extends the usefulness of the recovery process to metals that cannot be conveniently deposited as powders or flakes.
  • the high-pressure nozzles can also be used as an alternative method of removing powders or flakes.
  • the high-pressure fluid nozzles can be used instead of ultrasonic generators to remove electroplated metal deposits from the rotatable cathodes. Removing such deposits in the form of thin foils may require some modification of the reactor geometry in order to accommodate a practical recovery system for collecting the metal.
  • the invention thus provides apparatuses and methods for the recovery of metal from either an aqueous or non-aqueous solution, and the facile separation of electrochemically deposited metal or metallic compounds from an underlying cathode.
  • thin metallic films When thin metallic films are formed over a rotatable cathode under certain specific electrochemical conditions, they can be removed with high- pressure fluid nozzles sprayed directly on the rotatable cathode after electrodeposition.
  • the number of nozzles, spray angles, fluid pressure, distance between nozzles and targeted cathodic surface depend upon size of the reactor and number of cathodic faces.
  • the fluid nozzles can remove thin metallic foils, as well as powders or flakes, due to the high energetic physical contact between the flowable material and the interface between the metal itself and the surface of the cathode.
  • the foils can have a thickness of about 5 mm or less, of about 25 microns to about 5 mm, or of about 50 microns to about 3 mm.
  • the invention provides another type of mechanical means to recover metallic deposits obtained through the use of rotatable cathode, which is also applicable to metals that cannot conveniently be deposited as powders.
  • Such a method can be particularly suitable for the extraction of metallic deposits that are formed at cathodically polarized rotatable electrodes.
  • the method results in a breakage of the bonding linkage (interface) between the electrodeposited metallic foil and the surface of the cathode onto which it has been formed.
  • the energy that is transferred from the molecules of flowable material that arrive at high velocity at the interface weakens the mechanical bonding between the foil and the surface of the cathode. Hence, the foil is physically removed by detaching from the surface on which it was formed.
  • the nozzles can use water from the mains supply, which is pressurized with a compressor, but other liquid media may also be used.
  • the nozzles can be fed with deionized fluid (such as deionized water), or liquid that originates from the solution to be treated, mixtures of fluid and organic solvents in any combination and proportion, organic liquid only, or any pure or mixture of aqueous and nonaqueous liquids that may or may not include solid particles such as pellets, flakes or powder, made of polymer, ceramic or metal, and their combination thereof.
  • Liquid temperature can vary from near freezing to near boiling point.
  • the solid particles such as pellets, flakes or powder can be directed straight onto the cathode propelled by compressed air or fluid.
  • the pressure of the fluid can be, for example, at least 250, 300, 400 or 500 psi.
  • the pressure can also vary from 500 to 5000 psi, from 500 to 2000 psi, or from 1000 to 3000 psi. High pressures require more care since they may damage the rotatable electrode especially if the liquid medium contains solid particles.
  • the high-pressure fluid remove electrodeposited metal over the rotatable electrode when used as a cathode.
  • the way the energy is used to break the interface between the metal deposit and the cathode is by the initiation of a peeling effect at the metal-cathode boundary.
  • a high-pressure fluid hits an interface through a line-of-sight spray mechanism such as a nozzle.
  • the rotatable cathode can be provided with insulating masks to create zones where no metal deposition occurs. The masks create a discontinuity in the electrodeposited layer all over the cathode.
  • this foil non-uniformity weakness property to easily remove the metal.
  • the number, dimension, location and material of masks are variable.
  • the number of masks is such that depending upon the rotatable cathode diameter, the metal strips sizes produced by the fluid nozzles can be easily recuperated at the bottom of the reactor.
  • at least one non-conductive mask region can be present on the cathode so as to prevent the deposition of metal in the at least one mask region, whereby at least one nozzle can be directed at an edge of the foil formed at the periphery of the mask region so as to peel away the deposited foil from the cathode.
  • the at least one mask region can comprise a non-conductive strip applied to the surface of the rotatable cathode.
  • the mask regions can have a shape selected to facilitate the removal of the metal foil at the interface between the foil and the rotatable cathode.
  • the metal can be deposited as a foil
  • the rotating cathode contains mask regions where no metal is deposited so as to create edges on the deposited foil
  • the foil is removed by directing the flowable material at the edges so as to peel the foil off the surface of the cathode.
  • the electrochemical reaction can be periodically interrupted to permit the removal of the metal extracted from the solution with the flowable material.
  • the constraints for the fluid nozzles are not necessarily identical for the removal of metal foil on the external face and the internal face of a double-face rotating cathode.
  • the more rotating cathodes are present inside a reactor the greater the number of nozzles will be necessary to recover the electrodeposited metal over all available surfaces.
  • At least one nozzle is needed to strip the electrodeposited metal from a cathodic surface.
  • a nozzle is more efficient when it sprays at angle along all the surface of the cathode surface. Hence, the entire surface can be swept when the cathode is rotating.
  • the speed at which the cathode rotates can vary from about 0.5 to 25 m/s, (tangential speed). For example, it can rotate at a lower tangential speed at which it turns during the electrowinning cycle step. If the speed is too high, the metallic strips may be projected with unnecessary force and dispersed inside the reactor.
  • the entire stripping step can be done within the reactor full or empty from its liquid content, since the nozzles can be efficient both ways. By doing so, the stripping step can be performed within the reactor or inside another chamber if the reactor is equipped with a mechanical set-up that allows its displacement into another compartment. This latter option can facilitate the recovery of metallic strips. The fact that the strips are wet and are removed at high velocity may propel them toward the surrounding wall of the reactor and/or the anodes where they may adhere.
  • the reactor can be equipped with a set of screens that act as shields and avoid propelling metal strips over the anodes.
  • the screens can be held by the reactor cover or by any other means, as far as they are brought after the electrolysis cycle step; otherwise these screens will represent an obstacle if placed between the cathode and the anodes. Such screens can thus collect metallic strips of foil detached by the flowable material.
  • the rotatable cathode can be cylindrical, and the at least one nozzle can be located so as to direct the stream onto the surface of the cathode in a direction that is intermediate between a direction normal to the surface of the cathode and a direction tangential to the surface of the cathode.
  • the least one nozzle can be movable along a line parallel to the axis of the rotatable electrode.
  • At least one nozzle can comprise a mechanical array that permits the nozzle head to move along three orthogonal axes.
  • the at least one nozzle can be mounted in a housing located outside and/or inside the rotatable cathode. Alternatively, a set of nozzles can be in a housing fixed outside the cell.
  • the stream, before contacting the surface can be substantially aligned along a horizontal axis or along a vertical axis.
  • the electrolytic cell can comprise two concentric anodes having a generally cylindrical shape, defining a gap therebetween, and a rotatable cathode having a generally cylindrical shape disposed within the gap, the cathode being a double- faced cathode having a pair of opposed electrode faces and passages are defined between the outer face of the cathode and the outer anode and between the inner face of the cathode and the inner anode, the passages being adapted to receive the solution.
  • each of the anodes can comprise at least one aperture adapted to permit the passage of at least one stream of flowable material therethrough for dislodging the metal deposited on the cathode.
  • the anodes can also each comprise at least two curved sections forming the generally cylindrical shape, the sections defining therebetween at least one passage for directing at least one stream of flowable material therethrough for dislodging the metal deposited on the cathode.
  • the electrolytic cell can comprise a plurality of nozzles, which are substantially parallel to one another, substantially horizontally extending and disposed in a one above another relationship.
  • the electrolytic cell can comprise a plurality of nozzles, which are substantially parallel and spaced to one another, substantially horizontally extending and disposed in a one above another relationship.
  • the electrolytic cell can comprise a plurality of nozzles, the nozzles being disposed in such a manner so as to direct their respective streams onto the cathode in a direction that is intermediate between a direction normal to the surface of the cathode and a direction tangential to the surface of the cathode.
  • the electrolytic cell can comprise two sets of nozzles, an inner set adapted to direct streams of the flowable material onto the inner face of the cathode and an outer set adapted to direct streams of the flowable material onto the outer face of the cathode.
  • the counter electrode portions can define a channel receiving the rotatable electrode.
  • the rotatable electrode is cylindrical and the counter electrode portions define an annular channel accommodating a cylindrical wall of the rotatable electrode, wherein inner and outer surfaces of the cylindrical wall provide the opposite electrode faces.
  • the rotatable electrode and the counter electrode portions can have a common axis.
  • the radial distance from an inner electrode portion to the inner face of the rotatable electrode can be the same as the radial distance from the outer face of the rotatable electrode to the outer electrode portion.
  • the electrolytic cell can further comprise a meniscus-breaker to inhibit the rising of liquid in the cell at tangential speeds of the rotatable electrode (for example in excess of 1m/sec).
  • the meniscus-breaker can be shaped to permit the passage of liquid and solid particles downwardly and the evolution of gases from the cell upwardly.
  • the electrolytic cell can comprise a plurality of the rotatable electrodes located inside the cell cavity.
  • the electrolytic cell can further comprise a plurality of sets of the counter electrode portions located inside the cell cavity and associated with the respective rotatable electrodes.
  • the electrolytic cell can also comprise an internal holder for guiding and securing a shaft of the rotatable electrode.
  • the internal holder can be mounted on one or more legs placed in such a way that the holder is securely fixed inside the cell cavity and liquid flow is not restricted.
  • the cylindrical electrode has an opening to permit liquid to pass over either face of the rotatable electrode.
  • the counter electrode portions can have at least one opening to permit liquid to pass therethrough and so as to contact the opposite faces of the rotatable electrode.
  • the electrolytic cell can comprise at least one nozzle adapted for directing a stream of flowable material under pressure onto one of the opposite electrode faces of the rotatable electrode, and at least one nozzle adapted for directing a stream of flowable material under pressure onto the other one of the opposite electrode faces of the rotatable electrode.
  • the electrolytic cell can comprise a plurality of nozzles adapted for directing a stream of flowable material under pressure onto one of the opposite electrode faces of the rotatable electrode, and a plurality of nozzles adapted for directing a stream of flowable material under pressure onto the other one of the opposite electrode faces of the rotatable electrode.
  • At least one nozzle can be adapted to direct a stream on the surface at an angle about in the middle between an angle ⁇ of 90 °, and an angle
  • the at least one nozzle can
  • the at least one nozzle can be adapted to direct the at least one stream on the surface in a substantially vertical alignment.
  • Figure 1 is a schematic cross-section view of an electrolytic cell according to an embodiment
  • Figure 2 is a schematic top view of part of a rotating cathode of an electrolytic cell showing a possible fluid nozzles configuration according to an embodiment
  • Figure 3 is a schematic top view of part of a rotating cathode of an electrolytic cell showing a possible fluid nozzles configuration according to a further embodiment
  • Figure 4 is a schematic top view of part of a rotating cathode of an electrolytic cell showing a possible fluid nozzles configuration according to another specific embodiment
  • Figure 5 is a cross-sectional view of part of the electrodes of an electrolytic cell showing an example of fluid nozzles configuration according to another embodiment
  • Figure 6 is a cross-sectional view of part of the electrodes of an electrolytic cell showing an example of fluid nozzles configuration according to another embodiment
  • Figure 7 is a schematic cross-section view showing different configurations of mask strips used on a cathode of an electrolytic cell according to another embodiment
  • Figure 8 is a front perspective view of an electrolytic cell according to another embodiment, wherein a rotatable cathode is shown in a raised position and outside of a cell cavity;
  • Figure 9 is another perspective view of an electrolytic cell as shown in Fig. 9, in which two anodes are used;
  • Figure 10 is another perspective view of an electrolytic cell as shown in Fig. 9, in which a single anode is used.
  • Figure 11 is another perspective view of an electrolytic cell as shown in Fig. 9, in which several nozzles are shown.
  • the metal recovery apparatus shown in Figure 1 comprises an electrolytic cell 2, a meniscus-breaker 3, upper 4u and lower 4I mask plates for the rotatable electrode.
  • the rotatable electrode is a double-faced electrode as described in co- pending application no. 11/362,233, filed on 02/27/2006, which is hereby incorporated by reference in its entirety. Metal is deposited on both surfaces.
  • the cell 2 When being used, the cell 2 is filled by the solution to be treated and then cathode 7 is rotated and an electric current is applied to the electrodes. The metal is thus deposited uniformly on the cathode 7.
  • the metal When a double-face cathode is used (together with two anodes) the metal is deposited on both faces of the cathode.
  • the current is turned off and the remaining solution is removed.
  • streams produced by the nozzles are used so as to dislodge the metal from the cathode 7 while the latter is rotated so that the nozzles contact the whole surface of the cathode.
  • the metal recovered is then removed from the cell, for example by means of a filtration unit.
  • the meniscus-breaker 3 is a cover plate with a central opening that prevents the rotating liquid from rising up the walls of the chamber while allowing evolved gases to escape as described in the co-pending application referred to above.
  • the meniscus-breaker is important because at the high rotational speed the rotatable cathode is submitted, the electrolyte is thrown outward and tends to climb up the wall of the chamber. Apart from potentially causing the liquid to overflow the chamber, this effect reduces the contact of the electrolyte with the cathode and thus inhibits electrodeposition of the metal.
  • a nozzle 10 for stripping metal foil from the external face of the rotating cathode is located inside the housing 14 along with elevator screw 11 , compressor 12 and the elevator screw motor 13. Several nozzles can also be used and disposed around the cathode 7.
  • a second housing 17 for stripping metal from the internal face of the rotating cathode comprises a nozzle 20, the nozzle arm 15, compressor 21 and a motor 16 for rocking the nozzles.
  • the nozzle 20 is used to direct a stream of flowable material on the internal face of the cathode 7.
  • such a jet can also be used for treating the external face of the cathode 7.
  • the cell 2 can comprise a plurality of such nozzles disposed around the cathode 7.
  • Figure 1 represents one of the possible arrangements of the fluid nozzles, which remove metal from both faces of the rotating cathode.
  • Two separate nozzle housings 14 and 17 are present, one to strip metal from the outer face of the cathode and one for the internal face.
  • Each housing is adapted to its corresponding target.
  • the housing 14 for the external face is able to generate a stream of flowable material directed at right angle if necessary or directed in a substantially horizontal alignment.
  • the housing position is built differently and can be placed outside or inside the cell cavity. It is designed to shoot the fluid at an angle onto the internal face of the rotatable electrode.
  • the housing 17 for stripping metal from the internal face of the rotating cathode shown in Figure 1 can be placed outside the rotatable electrode, but can also be located inside the rotatable cathode when the dimension of the internal anode holder allows it. Then, the angle at which the stream is directed and the nozzle motion is determined accordingly.
  • One or more vertical non-conductive mask strips 6 can be located on both inner and outer faces of the rotatable cathode 7 so as to prevent electrodeposition over them. Since the external and internal diameters are similar for each double-face cathode, and since the wall is quite thin, the distance between two masks on both faces of each cathode can be relatively identical. Hence, metal foils removed from both faces during the action of fluid nozzles have almost the same length.
  • the mask strips could be in the form of applied dielectric material, such as a polymer, or alternatively the cylindrical rotatable electrode itself could be formed of a series of metal wall sections on a dielectric support with gaps between the sections to form the mask strips.
  • the electrolytic cell 2 is similar to the cell in the above referenced patent applications both in terms of material properties and assembly.
  • the electrolytic cell 2 can have at least two nozzles systems 10 (or one system 10 and one system 20) instead of ultrasonic generators to recover the electrowon metal from the rotating cathodes.
  • nozzles systems 10 or one system 10 and one system 20
  • the person skilled in the art would recognize that when a cell is a single-face cathode (a cathode having an external face combined with an anode having an internal face there is no need for a nozzle 20. In such a case, one or more nozzle 10 can be used.
  • the fluid nozzles are used to remove metal electrodeposited as foils although they can remove metal as powders or flakes as well. When used to remove powders or flakes, masks may not be necessary.
  • the fluid nozzles 10 and 20 can be operated by various mechanisms inside housings 14, 17. For example, one or several nozzles can remove metal foil over the external face of a cathode by sweeping its surface vertically using an endless screw-type 11 activated by an electrical motor 13. Fluid is supplied through an air compressor 12 connected to the nozzles by hoses or tubes. Another mechanism is shown in Figure 1 to remove metal foils on the internal face of a cathode. Fluid nozzles are held by an arm 15 inside which a transmission mechanism (not shown) allows a back-and-forth movement of the fluid nozzles. Hence, the rocking displacement of the head can remove the metal from bottom to top onto the internal face of the rotating cathode.
  • a trap mechanism is constructed between the cell wall and the housings. When the liquid is under electrolysis, the traps are closed. At the end of the electrolysis, the traps are opened allowing the nozzles head to be visible by the targeted cathode surfaces.
  • the counter-electrodes internal and external anodes, (not shown), are cylindrical and have each at least one aperture or space formed in them to allow the high- pressure nozzles to shoot directly onto the facing surface of the cathode. Shooting through any type of physical barrier will result in lack of removal efficiency. Factors that will influence the time period during which the nozzles are in use will vary according to the process.
  • Another factor influencing the nozzles period of use is the relationship between the number of nozzles and the surface of the rotating cathode. In fact, fewer nozzles can be compensated by the sweeping speed of these latter, and/or the fluid beam diameter and intensity. All these factors are adjusted in the perspective of decreasing the entire electrowinning cycle and providing the more economical reactor design as per its overall size.
  • two positioning axes can be determined for optimum metal foil removal depending on the metal to be removed and its thickness.
  • Figures 2 to 4 show examples of the positioning of the fluid nozzles for the removal of metal foil 22 on the external face of the cathode 7, considering the fact that the rotation direction is toward a fluid stream.
  • the optimum hit angle is a compromise somewhere between these two positions (i.e. the nozzle disposed in such a manner that its stream hits the interface at an angle ⁇ comprised between 90° and 180° and the distance is
  • d3 (for an example see Figure 3) because the nozzle at position d1 is closer to the target than d2 where the distance between the nozzle and the target is at its maximum value.
  • d3 for an example see Figure 3
  • the angle ⁇ (the measured angle formed with the cathode)
  • the nozzle heads can be fixed at an experimentally
  • a pre-determined nominal position for example position "C” shown in Figure 3
  • move along a certain distance over the "X" axis while their displacement on the "Y” axis see Figure 1 sweeps along the entire exposed surface of the cathode.
  • the heads are fixed for instance in the middle position of the "Y" axis and an up-and-down rocking movement does the same sweeping effect (see Figure 1).
  • a plurality of nozzles 10 can be disposed one above the other along the "Y" axis so as to cover the whole external surface of the cathode 7 when the latter is rotating (such an example is shown in Figure 8 with nozzles 110).
  • the nozzle 10 (or a plurality of nozzles 10) can be disposed at an angle different than perpendicular to the "X" axis (see position D in Figure 4 as opposed to positions A, B and C in Figure 3).
  • Figure 5 shows a double-faced cathode 7 and internal anode 23.
  • the nozzle 20 is directed at an angle to the metal deposited on the internal face of the cathode.
  • Another option is to have a plurality of nozzles 20 as shown in Figure 6 and which are disposed one above the other. For example, such nozzles can be substantially parallel to one another, substantially horizontally extending, and disposed in a one above another relationship.
  • the nozzles 20 can be spaced from one another (as shown in Figure 6) or contacting one another.
  • the nozzles 20 can also be disposed as shown in Figure 4 (see position D).
  • the apertures defined in the anode 23 permit to the streams of the nozzles 20 to pass therethrough and to dislodge the metal 22 on the cathode 7.
  • the nozzles 20 shown in Figure 6 can produce a stream that forms an angle a
  • all the nozzles (10 and 20) can be adapted so as to produce streams that form substantially the same angle ⁇ with the surface of the
  • the common value for the angle ⁇ of the nozzles 10 can be the
  • the nozzles 10 can each be adapted to produce a stream that will contact the cathode at a different angle e.g. if there are ten nozzles, they will produce streams hitting the cathode with ten different values of angle ⁇ . The same
  • an apparatus can comprise ten nozzles (for directing streams on a given face of the cathode) and each of them produces a stream forming an angle ⁇ of about 135° with the surface of the cathode or the deposited metal.
  • the apparatus can comprise eight nozzles: two nozzles being adapted to produce a stream forming an angle ⁇ of about 125°, two nozzles being
  • the nozzles can alternatively be substantially vertically extending and define an angle ⁇ as shown in Figure 5.
  • the nozzles are adapted to treat the internal face of the cathode can be adapted to have a rocking movement as shown in Figure 1.
  • the nozzle head motion can be a rocking movement that strips metal foil from a bottom (position A) to a top position (position B) as shown in Figure 5.
  • the nozzle head may have a stream angle movement similar to the one shown in Figure 1.
  • the nozzles used for dislodging the deposited metal on the inside face of the rotating cathode can be substantially the same as those used for dislodging the outside face of the rotating cathode. For examples, they can be similar or identical to the nozzles shown in Figures 2, 3, 4 or 8.
  • an electrolytic cell 102 comprising a housing 100 defining a cavity adapted to receive the rotating cathode 107 and the solution to be treated.
  • the cathode 107 is rotated by means of a rotating member 101 and the cathode is provided with a meniscus-breaker 103, which acts as previously defined.
  • the cell is also provided with a plurality of nozzles 110 adapted to direct a stream of flowable material so as to dislodge the metal deposited on the cathode 107.
  • the flowable material is distributed in the nozzles 110 via a conduit 111 , which is connected to a pump (not shown) or any device adapted to generate the desired pressure.
  • the nozzles 110 are horizontally extending and are disposed in a one above the other relationship. Cables 114 are used to connect the electrodes to a power source (not shown). As it can be seen in Figure 8, the cathode 107 does not include masks. However, if desired, such masks can optionally be provided.
  • the nozzles 110 are adapted to clean the entire cathode 117 length at once when the latter is rotated. The nozzles can have straight or diffused stream to ensure a complete coverage of the cathode surface and complete removal of the deposit. The double face cathode is rotated while the fluid nozzles are activated to ensure that the complete surface can be cleaned.
  • the electrolytic cell comprises an internal anode 123 and an external anode 125.
  • the two anodes define a gap 127 therebetween, and the gap 127 is adapted to receive the cathode 107.
  • passages adapted to receive the solution are thereby defined between the outer face 107 of the cathode and the external anode 125 and between the inner face of the cathode 107 and the internal anode 123.
  • the external anode 125 comprises two curved sections, which define therebetween a passage 129 that allow the streams produced by the nozzles 110 to contact the outer face of the cathode 107.
  • the internal anode 123 comprises two curved sections, which define therebetween a passage 131 that allow the streams produced by the nozzles 120 to contact the inner face of the cathode 107.
  • the electrolytic cell 102 comprises only one anode.
  • the cell 102 comprises only an external anode 125 i.e. there is no internal anode and no nozzles therefore as shown in Figure 9.
  • the deposit of metal will be made only on the outer face of the cathode 107.
  • the solution to be treated in thus comprised between the outer face of the cathode 107 and the anode 125.
  • the inner face of the cathode 107 can even be made of a non-conductive material.
  • FIG. 11 A possible configuration of the nozzles 110 is shown in Figure 11.
  • the fluid nozzles can remove metal foil 22 at the interface between the foil and the rotating cathode (substrate).
  • the interfaces are created by the use of masks 6 (see Figures 1 to 4, and 7) that can be inserted perpendicular to the cathode radius and having the same length than the exposed height of the cathode 7.
  • the width and depth of the masks are important factors when reactor efficiency is considered.
  • the number of masks times the width of each of them represents a portion of the cathode surface that is useless for electrowinning, the masks being made of a non-conductive material.
  • the reduction of the surface of a specific rotating cathode can be compensated by an increase of the cathode height.
  • FIG. 7 shows different mask arrangements (masks 6a, 6b, 6c and 6d).
  • the nozzle head 30 produces a fluid stream that flows as shown by arrow 31.
  • the foil "wall" provides appropriate removal conditions.
  • the foil wall may be taper or anchored on the perpendicular wall of the mask opening area in the cathode.
  • the mask design can be a concave to concave-deep geometry.
  • the fluid nozzles are capable of removing the metal foil when the cell cavity is empty and the cathode is rotating. Under this specific condition, the liquid pressure at which the foil is being hit propels strips of the foil toward facing obstacle such as an anode and the strips will eventually fall by gravity. Screens may be used to prevent metal strips to stick to reactor walls or anodes. When all metal strips fall down the reactor, they can be collected by a strainer, a filter or any other type of recovery system that catches solid material such as metal strips and allows liquid to flow through.
  • Examples 1 to 4 have been carried out with an electrolytic cell as shown in Figure 1 in which a single-face cathode was used.
  • Examples 5 to 8 have been carried out with an electrolytic cell as shown in Figures 8, 10, and 11 in which a single- face cathode was also used.
  • Example 1 A solution containing 800 ppm of nickel and 1 ,5 g/L of boric acid was treated by electrolysis during 60 minutes at a flow rate of 100 mL/minute and a current density of 50 mA/cm 2 .
  • the nickel was electrowon from the solution thereof in the form of a metal foil that was about 50 microns thick.
  • a single fluid stream at 1500 psi removed all the metal at a rate of 5-seconds/200 cm 2 with a sweeping speed of 1 cm/second along the "Y" axis and a shooting angle ⁇ of
  • Example 2 A solution containing 800 ppm of zinc at a pH of 6.5 was treated by electrolysis for 30 minutes at a flow rate of 200 mL/minute and a current density of 45 mA/cm 2 .
  • the zinc was electrowon from the solution thereof in the form of a metal foil that was about 50 microns thick.
  • a single fluid stream at 1000 psi removed all the metal at a rate of 5-seconds/200 cm 2 with a sweeping speed of 1 cm/second along the "Y" axis and a shooting angle ⁇ of 170°.
  • Example 3 A solution containing 1000 ppm of chrome at a pH of 2.0 was treated by electrolysis for 30 minutes at a flow rate of 100 mL/minute and a current density of 120 mA/cm 2 .
  • the chrome was electrowon from the solution thereof in the form of a metal foil that was about 50 microns thick.
  • a single fluid stream at 2000 psi removed all the metal at a rate of 5-seconds/200 cm 2 with a sweeping speed of 0.5 cm/second along the "Y" axis and a shooting angle ⁇ of 150°.
  • Example 4 A solution containing 10086 ppm of copper at a pH lower than 1 was treated by electrolysis for 35 minutes at a flow rate of 300 mL/minute and a current density of 200 mA/cm 2 .
  • the copper was electrowon from the solution thereof in the form of a metal foil that was about 0.1 mm thick.
  • a single fluid stream at 500 psi removed all the metal at a rate of 20-seconds/200 cm 2 with a sweeping speed of 2 cm/second along the "Y" axis and a shooting angle a of
  • Example 5 A solution containing 1000 ppm of copper sulfate in a 0.5 % sulfuric acid solution was treated in a continuous flow. A current density of 90 mA/cm2 with a cathode rotation speed of 200 rpm. The solution was circulated with a flow rate of 17.5 L/min. pH was about 1.1 at room temperature. Using these parameters, copper was recovered as a powder. Cathode cleaning, i.e. deposit removal, was achieved using 15 seconds of fluid nozzles with a pressure of 500 psi at an angle a of 135o.
  • Example 6 Copper foil having a thickness of about 0.1 mm was obtained while treating a solution containing 8500 ppm of copper sulfate in 5 % sulfuric acid. The solution was treated in batch until 95% of the copper was removed. Operating parameters were the same as the first example except that the pH was ⁇ 1. The copper foil deposit was removed using 30 seconds of fluid nozzles at a pressure of 500 psi and a spraying angle ⁇ of 135o.
  • Example 7 A solution containing 20330 ppm of nickel from a Watts-type bath was treated. A current density of 200 mA/cm2 was applied at the cathode while rotating at a speed of 250 rpm. Temperature changed from 20oC to 50oC during plating. The pH of the solution was about five. Solution was treated in batch until complete removal of nickel and a foil having a thickness of about 0.25 mm was obtained. Removal of the deposit was achieved using a spraying angle ⁇ of 135o
  • Example 8 A nickel concentration of 500 ppm from a Watts-type solution was recovered used. A flow rate of 0.5 L/min allowed a powder form recovery. Temperature was in the range of 5O 0 C and pH was kept constant at around four. Cathode was maintained at 200 mA/cm 2 with a rotation speed of 400 rpm. Powder removal was achieved using 30 seconds of water spray nozzles at an angle a of 90°.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electrolytic Production Of Metals (AREA)

Abstract

L'invention concerne une cellule électrolytique permettant la récupération de métal à partir d'une solution. La cellule comprend une cavité de cellule permettant de recevoir la solution ; une cathode tournante située à l'intérieur de la cavité ; une contre-électrode en relation espacée avec la cathode tournante. Un système de buse permet de diriger un fluide haute pression sur la cathode est utilisé pour déloger le métal extrait de la solution par une réaction électrochimique.
PCT/CA2007/000768 2006-05-03 2007-05-02 Cellule électrolytique comprenant des moyens permettant de déloger des dépôts électrolytiques d'une électrode WO2007124605A1 (fr)

Applications Claiming Priority (4)

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US74631906P 2006-05-03 2006-05-03
US60/746,319 2006-05-03
US88866507P 2007-02-07 2007-02-07
US60/888,665 2007-02-07

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11806728B1 (en) * 2018-12-21 2023-11-07 Samuel, Son & Co. (Usa) Inc. Automated cathode washing system

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6017428A (en) * 1997-07-16 2000-01-25 Summit Valley Equipment And Engineering, Inc. Electrowinning cell
WO2005026412A1 (fr) * 2003-09-16 2005-03-24 Global Ionix Inc. Cellule electrolytique destinee a eliminer un materiau d'une solution
CA2575195A1 (fr) * 2004-07-22 2006-02-23 Phelps Dodge Corporation Appareil pour la production de poudre metallique par extraction electrolytique
US20060243595A1 (en) * 2004-09-16 2006-11-02 Global Ionix Inc. Electrolytic cell for removal of material from a solution

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6017428A (en) * 1997-07-16 2000-01-25 Summit Valley Equipment And Engineering, Inc. Electrowinning cell
WO2005026412A1 (fr) * 2003-09-16 2005-03-24 Global Ionix Inc. Cellule electrolytique destinee a eliminer un materiau d'une solution
CA2575195A1 (fr) * 2004-07-22 2006-02-23 Phelps Dodge Corporation Appareil pour la production de poudre metallique par extraction electrolytique
US20060243595A1 (en) * 2004-09-16 2006-11-02 Global Ionix Inc. Electrolytic cell for removal of material from a solution

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11806728B1 (en) * 2018-12-21 2023-11-07 Samuel, Son & Co. (Usa) Inc. Automated cathode washing system

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