CN112210800B

CN112210800B - Electrolytic deposition line comprising a pre-stripping device

Info

Publication number: CN112210800B
Application number: CN201910631414.7A
Authority: CN
Inventors: 莱昂·克罗塞特
Original assignee: Lai AngKeluosaite
Current assignee: Lai AngKeluosaite
Priority date: 2019-07-12
Filing date: 2019-07-12
Publication date: 2023-08-25
Anticipated expiration: 2039-07-12
Also published as: CN112210800A

Abstract

The present invention relates to an electrowinning line comprising a pre-stripping device. An electrowinning line for recovering a target metal present in an electrolyte comprises a pre-stripping apparatus (40) comprising: a pre-peeling arm (20) of variable length and rotatable about a hinge, and a blade module (21) disposed at a free end of the pre-peeling arm, the blade module comprising two blades (22) forming a tip of the blade module and configured to move between a standby configuration and a pre-peeling configuration. The pre-stripping apparatus initiates a crack at an interface between the first and second major surfaces and the corresponding metal layer across substantially the entire width (W) of the cathode plate by a combination of rotation and extension of the length of the pre-stripping arm and moving the blades of the blade module between the standby configuration and the pre-stripping configuration. The use of a pre-stripping apparatus according to the present invention allows the stripping cycle to be reduced by about 28% relative to a stripping cycle without the use of a pre-stripping station.

Description

Electrolytic deposition line comprising a pre-stripping device

Technical Field

The invention is in the field of a production line of nonferrous metals by means of an electrowinning process (electrowinning process) comprising transporting a plurality of cathode plates coated with a metal layer on a first and a second main surface thereof from an electrolytic cell (cell) in the form of a bath filled with electrolyte to a stripping station for stripping the metal layer from the first and second main surfaces. In particular, the present invention relates to a pre-stripping apparatus configured for initiating a crack (ack) between a metal layer and first and second major surfaces of a cathode to facilitate stripping of the metal layer at a subsequent stripping apparatus on a production line. The use of the pre-stripping apparatus of the present invention can reduce the total stripping time by at least 25% and significantly reduce the number of breaks in the stripping line for unsuccessful stripping operations.

The terms pre-strip or pre-strip are sometimes used in the art to refer to the undesired and premature delamination of the metal layer from the major surface of the cathode plate. In this document, the term pre-stripping is used exclusively to refer to the operation of initiating a crack at the interface between the metal layer and the main surface of the cathode plate before stripping the metal layer from the main surface of the cathode.

Background

Nonferrous metals can be produced by an electrolytic deposition process. For example, zinc (Zn) may be obtained by zinc sulfate (ZnSO) ₄ ) Obtained by electrolysis of zinc sulphate (ZnSO ₄ ) By treating the mixture with dilute sulfuric acid (H) ₂ SO ₄ ) And leaching and roasting zinc concentrate. As illustrated in the inset of fig. 3, generalPassing an electric current between the anode 11A and the cathode 11C through a current path comprising ZnSO ₄ And H ₂ SO ₄ Pure metallic zinc may be deposited on the cathode 11C, which is typically made of aluminum or aluminum alloy. The total redox reaction is 2ZnSO ₄ +2H ₂ O→2Zn+2H ₂ SO ₄ +O ₂ . Nonferrous metals other than zinc can be produced by electrolytic deposition processes such as copper, gold, nickel, and the like. The invention is applicable to a production line for the electrolytic deposition production of any metal.

As schematically shown in fig. 3, on an industrial scale, the electrowinning line comprises an electrolytic cell 1 filled with an electrolyte 1e, in which interleaved anode plates 11A and cathode plates 11C are immersed in the electrolyte and arranged in a staggered sequence in a row to form a plurality of electrolytic cells of the type depicted in the illustrations of fig. 3. When a layer of metal is electrodeposited on the cathode plate 11C, the metal-coated cathode plate is thus retrieved from the electrolyte with a lifting device (crane) and brought to a conveyor 29 which drives and feeds the metal-coated cathode plate to a stripping station 50 for stripping the layer of metal from the cathode plate (see fig. 1 and 3).

The stripping station 50, which may be as described in WO2010000717, generally comprises two blades (blades) configured to extend along the interface between the cathode plate and the target metal layer deposited on both major surfaces of the cathode plate. The target metal layer 13 thus stripped is recovered by gravity and the uncoated cathode plate 11Cs is transferred to a cleaning station 60 where both major surfaces are scrubbed, brushed and cleaned. In the embodiment illustrated in step (D) of fig. 3, the stripped cathode plate is transferred to a cleaning station by driving the stripped cathode plate forward on a conveyor. However, this need not be the case, and the cleaning station 60 may be located at a location that is not reachable through the conveyor. In this case, the lifting device may be used to collect the stripped cathode plates and transfer them to the cleaning station. The cleaned uncoated electrode plates are transferred out of the cleaning station 60 and are ready to be gripped by the lifting device and transported back into the corresponding electrolytic cell for new deposition of the target metal (see fig. 3, steps (E) and (F)).

As shown in fig. 1, once loaded on conveyor 29, metal coated cathode plate 11C is driven and sent to stripping station 50, such as, but not limited to, a stripping station as described in WO 2010000717. The first metal coated cathode plate 11C is responsible for the stripping station and is brought to a stripping position within reach of the first and second blades 51, thus defining a time, tb=0 (see fig. 1 (B)).

In most cases, the first and second blades, or a pair of pre-stripping blades, integrated in the stripping station are driven vertically downward over a small portion of the height of the metal layer coating the cathode plate to initiate a crack between the two metal layers and the corresponding first and second major surfaces of the cathode plate. The knife was again driven upward in preparation for full peel. The pre-peeling operation may last for about 2.5s from time tb=0 (see fig. 1 (C)).

After crack initiation, the first and second blades 51 run over the entire height of the metal coating along the interfaces between the first and second major surfaces of the cathode and the corresponding first and second metal layers. This operation is made possible by the cracks formed during the previous step, allowing the first and second blades to be interposed between the cathode plate and the metal layer. Then, the blades are moved to their initial positions, and thus the peeled metal layers fall down by gravity and are collected by a second conveyor (see fig. 1 (D) and 1 (E)). The stripping step may take about 5s and the pre-stripping and stripping steps total about 7.5s.

The stripped cathode plate 11Cs is thus discharged from the stripping station, for example onto conveyor 29, for further operations including, for example, cleaning and immersion in electrolyte 1e between the two anode plates 11A. Meanwhile, the next metal-coated cathode plate 11C is responsible for preparing it for stripping, thus closing the stripping cycle of the metal-coated cathode plate 11C, which lasts for about 9s in total, i.e. yields a productivity of about 400 plates per hour (pl./h) (see fig. 1 (F)).

As illustrated in fig. 2, the stripping station 50 may be preceded by a pre-stripping station 40 for initiating a crack between the metal layer and the cathode plate surface. The pre-stripping station can theoretically reduce the overall duration of the stripping cycle because the pre-stripping and stripping operations can run in parallel on two different plates instead of running in series on the same plate as described above with reference to fig. 1. For example, CN206599617U describes a pre-stripping apparatus comprising two jaws (jaws), each terminating in two blades distributed over the lips of each jaw. The jaws are configured for closing the blade against each of the first and second major surfaces of the metal-coated cathode plate and for driving vertically downward a limited distance to initiate a crack between the metal layer and the corresponding major surface of the cathode plate. This type of pre-stripping apparatus has a design similar to that of the stripping apparatus, with shorter (and stronger) jaws, as the blades do not need to run all the way down to the lower edge 11d of the cathode plate. The shorter jaws are stronger, allowing for the application of a stronger clamping force required to initiate the crack.

This solution is interesting but does not guarantee a reliable pre-peeling operation. The problems with such pre-stripping devices are:

The two blades terminating each jaw are long enough to extend over a large part of the width W of the metal layer, but therefore require a high force to insert the two long blades between the metal layer and the main surface, or

The two blades are short enough to reduce the required force, but the crack between the metal layer and the main surface is discontinuous, with the crack portions of the interface separated by unaffected interface areas.

This disadvantage does not allow to ensure a successful pre-peeling close to 100% and may even create more peeling line breaks than without the pre-peeling station, since the formation of cracks at the interface is not reproducible under such conditions. Note that the same problems as discussed in relation to the apparatus described in CN206599617U apply of course to vertically moving jaws provided with a single blade or with more than two blades.

From the foregoing, it can be seen that the stripping cycle still has a duration that limits the productivity of the electrowinning apparatus, whether or not a pre-stripping station is used. The present invention proposes a solution for reducing the duration of the peeling cycle and at the same time improving the reproducibility of the peeling operation, thus significantly reducing the number of interruptions of the peeling line. These and other advantages are described in detail in the following sections.

Summary of The Invention

The invention is defined in the appended independent claims. Preferred embodiments are defined in the dependent claims. In particular, the invention relates to an electrowinning line for recovering target metals electrolytically coated on a cathode plate, comprising:

a plurality of cathode plates comprising a first main surface and a second main surface separated by a cathode plate thickness and delimited by a perimeter having an upper edge provided with a cathode rim and a lower edge opposite the upper edge, the first main surface and the second main surface each being coated with a metal layer of the target metal, the metal layer extending over a layer height H13 measured between the lower edge and a layer upper edge of the metal layer and delimiting a coated plate thickness,

a conveyor extending along the longitudinal axis X1, the conveyor being configured for holding the cathode plate vertically with the cathode edge positioned upwards, and for conveying the cathode plate with the first and second main surfaces perpendicular to the longitudinal axis X1, first

o transferring the cathode plate to a pre-stripping zone (pre-stripping location) within the opening of the frame of the pre-stripping apparatus 40, the pre-stripping apparatus 40 defining an operating plane perpendicular to the longitudinal axis X1 and being configured parallel to the cathode plate for initiating a crack between each of the first and second main surfaces of the cathode plate and the upper edge of the layer of target metal to form a pre-stripped cathode plate, and further

o transporting the cathode plate to a stripping location within an opening of a frame of a stripping apparatus configured to strip and recover a layer of target metal from a first major surface and a second major surface of a pre-stripped cathode plate,

wherein, pre-stripping equipment:

comprising a pre-stripping arm, said pre-stripping arm

o has a degree of freedom parallel to the operating plane and rotating about a hinge coupled to the frame, rotation of the pre-peel arm about the hinge being driven by a tilt actuator, and

o has an axial degree of freedom allowing a variation in the length of the pre-stripping arm comprised between the hinge and the blade module tip at the first free end of the pre-stripping arm, the variation in length being driven by a length actuator selected from hydraulic, pneumatic or electric pistons,

wherein the tilt actuator and the length actuator are configured to move the pre-peel arm between:

o a standby position in which the pre-stripping arm does not interfere with the transport of the cathode plate, o a start position in which the tip of the blade module is in a position relative to the cathode plate at the pre-stripping location, the position being comprised between the cathode edge and the layer upper edge of the metal layer, and

o a pre-strip position in which the tip of the blade module is in a position relative to the cathode plate positioned at the pre-strip location, the position being comprised between the layer upper edge of the metal layer and the lower edge of the cathode plate,

wherein the blade module is provided with two blades positioned on either side of the operating plane and forming the tip of the blade module and configured for movement between:

o standby configuration, characterized by: the standby distance d0 between the blades being greater than the thickness of the cathode edge, allowing the pre-stripping arm to be moved from the standby position to the starting position, and

o pre-peel configuration, characterized by: the pre-strip distance d1 is less than the standby distance (d 1< d 0) and is included between the cathode plate thickness and the coated plate thickness.

The tilt actuator may be selected from a hydraulic, pneumatic, or electric piston including a first end coupled to the frame and a second end coupled to a second free end of the pre-stripper arm opposite and spaced from the tip of the blade module by a hinge.

In a preferred embodiment, the blade module comprises,

a blade module frame comprising a first branch and a second branch separated by a gap,

First and second elongated jaws, each elongated jaw comprising a drive end and a blade end opposite the drive end and being rotatably coupled to the first and second branches with a jaw hinge spaced from the drive end and the blade end, the blade end of each of the first and second elongated jaws being provided with a blade,

a clamping actuator selected from hydraulic, pneumatic or electric pistons, the clamping actuator comprising a cylinder fixed to the blade module frame and a piston fixed to a clamping mechanism comprising,

first and second beams, each comprising a first end rotatably coupled to a free end of a piston of the clamping actuator, and a second end rotatably coupled to a driving end of a corresponding elongated jaw, such that translation of the piston by a closing distance δ relative to a cylinder of the clamping actuator drives pivoting of the first and second elongated jaws about the respective jaw hinges, and thus moves the blade between the standby configuration and the pre-peeling configuration.

In this embodiment, it is preferred that the first beam and the second beam form an angle comprised between 160 ° and 180 ° when the blade is in the pre-peel configuration. This allows the blade module to be blocked in the pre-peel configuration.

In an alternative embodiment, the blade module comprises,

a clamping actuator system comprising,

o a first and a second clamping actuator selected from hydraulic, pneumatic or electric pistons, comprising a cylinder fixed to the blade module frame and a piston coaxially arranged and facing away from each other, each clamping actuator comprising a cylinder fixed to the blade module frame and a piston having a free end coupled to the driving end of the corresponding elongated jaw, or

A double-acting clamping actuator selected from double-acting hydraulic, pneumatic or electric pistons comprising a cylinder fixed to the blade module frame and two spaced pistons coaxially arranged and having free ends facing away from each other, the free end of each of the two spaced pistons being coupled to the driving end of a corresponding elongated jaw,

Translating the piston a closing distance relative to the cylinder of the clamping actuator system drives the pivoting of the first and second elongated jaws 21a about the respective jaw hinges and thus moves the blade 22 between the standby and pre-peeling configurations.

The pre-stripping apparatus preferably comprises a blocking element for securing the cathode plate at the pre-stripping location. The blocking member prevents the cathode plate from moving during the pre-stripping operation.

The blade modules preferably have a thickness measured parallel to the longitudinal axis X1 that is less than the distance separating every other cathode plate disposed on the conveyor (i.e., the distance between two plates on either side of the third plate between the two plates). In this way, the conveyor need not be equipped with a decoupling system (decoupling system) to bring the individual sheets into the pre-stripping position.

Preferably, the distance Δ between the upper edge of the layer and the tip of the blade module at the pre-peel location does not exceed 50% of the layer height H13 (i.e., Δ+.50% H13). The distance delta may be comprised between 150mm and 300mm (i.e. delta = 150mm to 300 mm).

The electrolytic deposition line of the present invention is suitable for stripping a target metal layer selected from zinc, copper, nickel or gold.

The invention also relates to a method for stripping an electrodeposited target metal layer on a first surface and a second surface of a cathode plate by an electrodeposition process, the method comprising the steps of.

Providing an electrowinning line as defined above,

transferring the cathode plate coated with a layer of the target metal on the first and second main surfaces to a pre-stripping location within an opening of a frame of a pre-stripping apparatus,

initiating a crack between each of the first and second main surfaces of the cathode plate and the corresponding layer of target metal, starting from the upper edge of the layer, to form a pre-stripped cathode plate,

transporting the pre-stripped cathode plate to a stripping position within the opening of the frame of the stripping apparatus,

stripping the target metal layer from the first and second major surfaces of the pre-stripped cathode plate and recovering the stripped target metal layer,

characterized in that the step of initiating the crack is performed as follows:

when the cathode plate is transferred to the pre-stripping zone, the pre-stripping arm is in the standby position, and the blade module is in the standby configuration,

once the cathode plate is in the pre-stripping zone, the pre-stripping arm is moved from the standby position to the starting position,

at the start position, by reducing the distance between blades from the standby distance d0 to the pre-peel distance d1, the blade module is brought to the pre-peel configuration,

By extending the length of the pre-peel arm from a start length Lc to a pre-peel length L1 that is greater than the start length (Lc < L1), the blade module is moved from the start position to the pre-peel position in the pre-peel configuration to insert the blade of the blade module between the metal layer and the corresponding first and second major surfaces, thereby creating an initial delamination area at the level of a portion of the upper edge of the layer.

Rotating the pre-stripping arm about the hinge 20h until the tip of the blade module is located between the cathode edge and the layer upper edge of the metal layer, so as to extend the initial delamination area to a large part of the layer upper edge, and preferably the entire width W of the layer upper edge, then

Bringing the blade module to a standby configuration by increasing the distance between the blades from the pre-peel distance d1 to the standby distance d0, and

move the pre-peel arm back to the standby position.

In a preferred embodiment, at the standby position, the pre-peeling arm has a contact length Lc and forms a standby angle greater than zero with the vertical direction at the level of the hinge, and the movement of the pre-peeling arm from the standby position to the start position is performed by rotating the pre-peeling arm to reduce the angle formed with the vertical direction at the level of the hinge from the standby angle to a start angle smaller than the standby angle, preferably the start angle is zero.

In an alternative embodiment, in the standby position, the pre-peeling arm has a standby length L0 smaller than the start length Lc and forms a standby angle of zero with the vertical direction at the horizontal plane of the hinge, and the movement of the pre-peeling arm from the standby position to the start position is performed by increasing the length of the pre-peeling arm from the standby length L0 to the start length Lc while keeping the standby angle of zero constant.

The method may include a safety procedure that is activated if a force required to move the pre-peel arm of the blade module from the start position to the pre-peel position in the pre-peel configuration exceeds a threshold force value by extending a length of the pre-peel arm. The security procedure comprises the following steps:

by increasing the distance between the blades from the pre-peel distance d1 to the standby distance d0, then by bringing the pre-peel arm to the starting position, the blade module is brought to the standby configuration,

at the start position, the blade module is brought to the pre-peeling configuration by reducing the distance between the blades from the standby distance d0 to the pre-peeling distance d1, and

by extending the length of the pre-peel arm from the starting length Lc to the pre-peel length L1, the blade module is again moved from the starting position to the pre-peel position in the pre-peel configuration.

The cycle time for performing all the steps of the present method is less than 8 seconds per plate, preferably less than 7 seconds, more preferably no more than 6.5 seconds.

The invention also relates to a pre-stripping apparatus for use in an electrowinning line as described above, the pre-stripping apparatus comprising:

a frame comprising an opening defining a pre-peeling zone, the pre-peeling zone being comprised in an operating plane perpendicular to the longitudinal axis X1,

a pre-stripping arm which is provided with a pre-stripping arm,

wherein the tilt actuator and the length actuator are configured for moving the pre-stripper arm between

o pre-peel configuration, characterized by: a pre-strip distance d1 is less than the standby distance d1< d0 and is included between the cathode plate thickness and the coated plate thickness.

Drawings

For a fuller understanding of the nature of the present invention, reference should be made to the following detailed description taken in connection with the accompanying drawings in which:

fig. 1: the steps of a peeling cycle according to the prior art are shown without the inclusion of a pre-peeling station.

Fig. 2: there is shown the steps of a stripping cycle comprising a pre-stripping station according to the present invention.

Fig. 3: various stages of a metal electrowinning line are shown, including an electrolytic cell, a pre-stripping station, a stripping station and a cleaning station, and a lifting device to remove the cathode plate from the electrolytic cell and to move it to the electrolytic cell.

Fig. 4: a first embodiment of a pre-stripping apparatus according to the invention is shown, wherein the pre-stripping arm: (a) at a standby position, (b) at a start position, (c) at a pre-peeling position, (d) during a pre-peeling operation, and (e) returning to the standby position.

Fig. 5 shows a second embodiment of a pre-stripping apparatus according to the invention, wherein the pre-stripping arm: (a) at a standby position, (b) at a start position, (c) at a pre-peeling position, (d) during a pre-peeling operation, and (e) returning to the standby position.

Fig. 6: a first embodiment of a blade module is shown with (a) a pre-peel arm in a start position and the blade module in a standby configuration, and (b) the blade module in a pre-peel configuration, and (c) the pre-peel arm in a pre-peel position, the blade module in a pre-peel configuration.

Fig. 7: a second embodiment of the blade module is shown with (a) the pre-peel arm in a start position and the blade module in a standby configuration, and (b) the blade module in a pre-peel configuration, and (c) the pre-peel arm in a pre-peel position, the blade module in a pre-peel configuration.

Detailed Description

The present invention relates to an electrodeposition line for recovering a target metal 13 electrolytically coated on a cathode plate 11C. The target metal may be selected, for example, from zinc, copper, nickel or gold. As schematically illustrated in fig. 3, an electrowinning line generally comprises one or more cells 1 filled with electrolyte 1e, and each cell is configured for immersing a plurality of electrode plates consisting of interleaved cathode and anode plates 11C, 11A. Current flows from the anode plate to the cathode plate through the electrolyte 1e, resulting in a metal layer being deposited on the main surface of the cathode plate facing the anode plate. Since both sides of the cathode plate are anode plates on both sides thereof, the metal layer 13 is deposited on the first and second main surfaces of the cathode plate during the electrodeposition operation. When the metal layer has reached the target thickness, the lifting device 30 is typically used to transport several such metal coated cathode plates 11C at a time from the electrolytic cell 1 to another location of the metal electrowinning line. For example, the lifting device may transport about 50 to 60 electrode plates at a time, in some cases, across the entire length of the electrolytic cell.

The cathode plate 11C includes a first major surface and a second major surface separated by a cathode plate thickness and bounded by a perimeter. The perimeter comprises an upper edge provided with a cathode rim 11r and a lower edge 11d opposite the upper edge. The first and second main surfaces are each coated with a metal layer of a target metal 13 extending over a layer height H13 measured between a lower edge 11d and an upper layer edge 13u of the metal layer and defining a coated plate thickness. The metal layer height H13 corresponds to the depth of immersion of the cathode plate in the electrolyte 1.

As shown in fig. 3, conveyor 29 extends along longitudinal axis X1, is configured for holding the cathode plate vertically with cathode edge 11r positioned upward, and is configured for conveying cathode plate 11C with the first and second major surfaces perpendicular to longitudinal axis X1. The conveyor is fed as follows:

feeding the cathode plate 11C into a pre-stripping zone within the opening of the frame of a pre-stripping apparatus 40, the pre-stripping apparatus 40 defining an operating plane perpendicular to the longitudinal axis X1 and configured for initiating a crack between each of the first and second main surfaces of the cathode plate and the layer upper edge 13u of the target metal layer to form a pre-stripped cathode plate 11Cp; the pre-stripping apparatus may include a blocking element (blocking elements) for securing the cathode plate at the pre-stripping location.

Feeding the pre-stripped cathode plate 11Cp to a stripping zone within the opening of the frame of the stripping apparatus 50, the stripping apparatus 50 being configured for stripping and recovering the stripped target metal layer from the first and second main surfaces of the pre-stripped cathode plate 11Cp, and preferably

The stripped cathode plate 11Cs is fed to a cleaning device 60 for cleaning the main surfaces of the stripped cathode plate, producing a cleaned cathode plate 11Cc that can be returned to the electrolytic cell 1. The latter operation is typically performed with a lifting device. Depending on the particular arrangement of each electrowinning line, the stripped cathode plate may be transported to a cleaning station 60 with a lifting device.

The gist of the present invention is the use of a novel pre-stripping apparatus 40, which pre-stripping apparatus 40 produces a high level of reproducibility, allowing a significantly reduced time for the stripping cycle compared to the duration of the stripping cycle without the pre-stripping apparatus (as illustrated in fig. 1). Fig. 2 gives an estimate of the time reduction achieved by an electrowinning line according to the invention, which may be about 28% shorter than the line illustrated in fig. 1. In particular, when a peeling rate of 400 plates/hour can be achieved according to the conventional peeling cycle of fig. 1, the peeling rate can be increased to 554 plates/hour by including a pre-peeling apparatus 40 according to the present invention upstream of the peeling apparatus 50.

Various elements of the electrowinning line according to the invention are reviewed below.

Electrolytic cell 1, electrolyte 1e and cathode plate 11C

The electrowinning line of the invention may comprise one or more electrowinning stagesA solution cell 1, the one or more electrolytic cells extending over a length along an axis Y and over a width along an axis X and having a depth defined along an axis Z, wherein X ζ Y ζ Z. Quantity i>1 cell may be aligned along axis X. They are filled with an electrolyte 1e, which electrolyte 1 e) consists of a liquid leaching solution containing ions of the target metal. For example, in order to produce zinc (Zn) as the target metal 13, the electrolyte 1e is typically zinc sulfate (ZnSO ₄ ) In sulfuric acid (H) ₂ SO ₄ ) (see inset of figure 1).

The electrode plates are composed of a cathode plate 11C and an anode plate 11A, each of which includes a first main surface and a second main surface that are spaced apart from each other by the thickness of the electrode plates. Wherein the cathode plate 11C and the anode plate are made of a material different from the target metal. For example, for electrolytic deposition of Zn, the cathode plate 11C may be made of aluminum or an aluminum alloy, and the anode plate 11A may be made of a lead alloy. For electrolytic deposition of copper (Cu), the cathode plate 11C may be made of stainless steel, and the anode plate 11A) may be made of lead alloy. The electrode plates may have various sizes, but may have a width W of about 100cm and a height H of about 180-200 cm. The cathode plate is delimited by a perimeter having an upper edge provided with a cathode rim 11r and a lower edge 11d opposite the upper edge. The cathode plate is received by conveyor 29 with the upper edge and cathode edge 11r oriented upward and the lower edge 11d oriented downward. As shown in fig. 3, the major surfaces of the cathode plates face each other and are parallel to each other.

The metal layer of the target metal covers the entire width W of the first and second main surfaces and extends from the lower edge 11d to the layer upper edge 13u over a height H13, which height H13 is smaller than the height H of the cathode plate. Thus, on each side of the cathode plate, an uncoated cathode main surface remains between the layer upper edge 13u and the cathode edge 11 r. These bars correspond to the portions of the cathode plate that are exposed from the electrolyte. Strips of the uncoated major surface are important because they allow positioning of the blade modules of the pre-peel arm to a starting position ready for performing the pre-peel operation.

Pre-stripping apparatus 40

The cathode plate 11C is loaded with a layer of the target metal 13 coated on each of the first and second main surfaces of the cathode plate 11C, which cathode plate 11C is fed one at a time by a conveyor to the pre-stripping apparatus 40.

The pre-stripping apparatus comprises a frame 40f provided with an opening perpendicular to the longitudinal axis X1 and defining a pre-stripping zone in which the cathode plate must be positioned and held in place for a pre-stripping operation to take place in which the main surface of the cathode plate is perpendicular to the longitudinal axis X1.

The pre-peeling apparatus comprises a pre-peeling arm 20, the pre-peeling arm 20 having a degree of freedom parallel to the operating plane and rotating about a hinge 20h, the hinge 20h defining an axis of rotation parallel to the longitudinal axis X1 and being coupled to a frame 40f. The rotation of the pre-peel arm about the hinge is driven by a tilt actuator 27. The tilt actuator may be selected from a hydraulic, pneumatic, or electric piston, including a first end coupled to the frame 40f and a second end coupled to a second free end of the pre-stripper arm opposite the tip of the blade module and spaced from the tip of the blade module by a hinge 20 h.

The pre-peel arm 20 also has an axial degree of freedom allowing for variations in the length of the pre-peel arm, including between the hinge and the tip of the blade module 21 at the first free end of the pre-peel arm. The pre-stripping arm may consist of, on the one hand, a main arm portion 20a coupled to the frame by a hinge and having a free end coupled to the tilt actuator 27 and, on the other hand, an extension arm portion 20b comprising a free end holding the blade module 21. The change in length is obtained by translating an elongated arm portion 20b with respect to a main arm portion 20a, which is driven by a length actuator selected from hydraulic, pneumatic or electric pistons.

The tilt actuator and the length actuator are configured to move the pre-peel arm between,

a standby position (see fig. 4 (a) and 5 (a)), in which the pre-stripping arm does not interfere with the transport of the cathode plate 11C,

a start position (see fig. 4 (b) and 5 (b)) in which the tip of the blade module is in a position relative to the cathode plate 11C at the pre-stripping zone, the position being included in a strip of the uncoated main surface defined between the cathode edge 11r and the layer upper edge 13u of the metal layer, and

a pre-strip position (see fig. 4 (C) and 5 (C)) in which the tips of the blade modules are in a position relative to the cathode plate 11C positioned at the pre-strip location, which is comprised between the layer upper edge 13u of the metal layer and the lower edge 11d of the cathode plate, between the target metal layer and the corresponding main surface. In the pre-peel position, the tip of the blade module is preferably less than 1/2H13 from the layer upper edge 13 u.

As illustrated in fig. 6 and 7, the blade module 21 is provided with two blades 22, which two blades 22 are positioned on either side of the operating plane and form the tip of the blade module. The two blades are configured for movement between:

standby configuration (see fig. 6 (a) and 7 (a)), characterized by: the standby distance d0 between the blades, measured parallel to the longitudinal axis X1, being greater than the thickness of the cathode edge 11r, allows the blade module to move from the standby position to the starting position, and

pre-peel configuration (see fig. 6 (b) and 6 (c) and 7 (b) and 7 (c)), characterized as: the pre-strip distance d1 is less than the standby distance (d 1< d 0) and is included between the cathode plate thickness and the coated plate thickness.

Pre-stripping arm 20

The gist of the invention is the use of a combination of translational and rotational movements of a pre-stripping arm and a blade module attached to the pre-stripping arm for pre-stripping a metal layer of the target metal of the cathode plate. The translational movement is at least used to drive the pre-peel arm and blade from a start position to a pre-peel position, moving the wedge-like blade to create a first crack at the interface between the main surface and the corresponding metal layer. The rotational movement serves to propagate the first crack along the entire width W of the layer upper edge 13 u.

The combination of translational and rotational movement is advantageous over prior art pre-stripping devices that rely solely on translational movement (as described for example in CN 206599617U) because the blade may have a much smaller width than prior art blades, which must extend over a substantial portion of the width of the metal layer. In the case of narrowing of the blade, for a given force, the stress applied at the interface between the cathode main surface and the corresponding metal layer increases proportionally (σ=f/a, where F is the applied force, a is the area where the force is applied, and σ is the corresponding stress). With the stress significantly higher than the adhesive strength of the interface applied very locally at the end of the layer upper edge 13u, the blade can initiate a crack between the metal layer and the corresponding main surface by penetrating along the interface, except for very exceptional cases. The rare case where the blade will not penetrate along the interface will correspond to the case where the adhesion between the metal layer and the main surface is abnormally high for some reason. For example, if residue or corrosion of the coating has occurred on the main surface of the cleaned cathode 1Cc when introduced into the electrolytic cell for electrodeposition.

Fig. 4 and 5 show two embodiments of the pre-peeling apparatus, which are different from each other mainly in the configuration for bringing the pre-peeling arm from the standby position to the start position and returning to the standby position after the pre-peeling operation.

According to the embodiment illustrated in fig. 4, pre-peel arm 20 may change its length between contact length Lc and pre-peel length L1 by translating extension arm portion 20b relative to main arm portion 20a, where Lc < L1. The length of the pre-peel arm is defined between the hinge 20h and the tip of the blade module. In the standby position (see fig. 4 (a)) the pre-strip arm has a contact length Lc and is inclined at an angle to the vertical axis Z such that the channel is clear for the cathode plate to be brought into the pre-strip position within the opening defined by the frame. The blade module is in a standby configuration with the blade at a standby distance d0 (see fig. 6 (a) and 7 (a)).

The blade module 21 is brought to the starting position by rotating the pre-stripping arm about a hinge (parallel to the longitudinal axis X1) until a substantially vertical position parallel to the axis Z is reached. With the blade module in the standby configuration, the blade may pass either side of the cathode edge 11r as the pre-peel arm rotates. When the pre-stripping arm with contact length Lc reaches a vertical orientation, the two blades face the corresponding strips of the uncoated major surface of the cathode plate, which are defined between the layer upper edge and the cathode edge (see fig. 4 (b)). At this time, the blade moves from the standby configuration to the pre-peeling configuration in a manner explained later. Thus, the blade contacts or nearly contacts (or taps) the uncoated strip of the major surface of the cathode plate.

As illustrated in fig. 4 (c), the extension arm portion 20b is then moved relative to the main arm portion 20a to increase the length of the pre-peel arm by a distance d from the contact length Lc to the pre-peel length L1 (i.e., d=l1-Lc) such that the tip of the blade module 21 exceeds the layer upper edge 13u by a distance Δ thereof. With the blades in their pre-peel configuration, with this translation, the blades penetrate along the interface between the metal layer and the corresponding main surface like two thin wedges, exerting a stress higher than the adhesive strength of the interface, and thus inducing a first crack of small size (measured parallel to axis Y1, where X1 Σ1 Σz) with respect to the width of the metal layer. Only the first crack is too small for any use of the first crack for a subsequent stripping operation. On the other hand, due to the smaller width of the blades, these blades are prone to penetration along the interface between the metal layer and the first and second major surfaces.

As shown in fig. 4 (d), the pre-peeling arm is then rotated about the hinge 20h, thus driving the blade along the width of the metal layer, thus causing the first crack to propagate along the entire width of the metal layer and completing the pre-peeling operation.

When the rotation of the pre-strip arm drives the blades over the upper layer edge of the metal layer, the blade module is brought to a standby configuration, increasing the distance between the blades from the pre-strip distance d1 to a standby distance d0, to allow the arm to continue its operation as the blades pass over the cathode edge 11 r. Further, as shown in fig. 4 (e), the pre-peeling arm is shortened from the pre-peeling length L1 to the contact length Lc, thereby returning the pre-peeling arm to the standby position. The pre-stripping operation is thereby completed and the pre-stripped cathode plate 11Cp may be removed from the pre-stripping apparatus 40 and driven to the stripping apparatus 50 and a new coated cathode plate may be brought into the pre-stripping position.

According to an alternative embodiment shown in fig. 5, the pre-peel arm 20 may change its length between a standby length L0 and a pre-peel length L1 (via a contact length Lc) by translating the extension arm portion 20b relative to the main arm portion 20a, where L0< Lc < L1. In the standby position (see fig. 5 (a)), the pre-stripping arm has a contact length L0 and remains perpendicular, parallel to the axis Z, so that the channel is clear for the cathode plate to enter the pre-stripping position within the opening defined by the frame. The blade module is in the standby configuration and the blades are at a standby distance d0 (see fig. 6 (a) and 7 (a)).

The blade module 21 is brought to the start position by extending the pre-peeling arm from the standby length L0 to the contact length Lc by translating the extension arm portion 20b relative to the main arm portion 20 a. When the blade module is in the standby configuration, the blade may pass either side of the cathode edge 11r as the extension arm portion 20b translates. When the pre-stripping arm reaches the contact length Lc, the two blades face the corresponding strips of the uncoated major surface of the cathode plate, which are defined between the layer upper edge and the cathode edge (see fig. 5 (b)). At this time, the blade moves from the standby configuration to the pre-peeling configuration in a manner explained later. Thus, the blade contacts or nearly contacts (or taps) the uncoated strip of the major surface of the cathode plate.

As shown in fig. 5 (c), the extension arm portion 20b is then moved again relative to the main arm portion 20a to further increase the length of the pre-peel arm by a distance d from the contact length Lc to the pre-peel length L1 (i.e., d=l1-Lc) such that the tip of the blade module 21 exceeds the layer upper edge 13u by a distance Δ from the layer upper edge. With the blade in its pre-peel configuration, by this translation, the blade penetrates along the interface between the metal layer and the corresponding main surface like two thin wedges, exerting a stress higher than the interface strength between the metal layer and the main surface and thus inducing a first crack of small size with respect to the width of the metal layer (measured parallel to axis Y1, where X1 Σ1). Only the first crack is too small for any use of the first crack for a subsequent stripping operation. On the other hand, due to the smaller width of the blades, these blades are prone to penetration along the interface between the metal layer and the first and second major surfaces.

As shown in fig. 5 (d), the arm is then rotated about the hinge 20h to drive the blade along the width of the metal layer, thereby causing the first crack to propagate along the entire width of the metal layer and completing the pre-peeling operation.

When the rotation of the pre-stripping arm drives the blades over the upper layer edge of the metal layer, the blade module is brought to a standby configuration, increasing the distance between the blades from the pre-stripping distance d1 to a standby distance d0, allowing the arm to continue its operation as the blades pass the cathode edge 11 r. Further, as shown in fig. 5 (e), the pre-peeling arm shortens from the pre-peeling length L1 to the standby length L0, and rotates back to a vertical position (not shown) to bring the pre-peeling arm back to the standby position. The pre-stripping operation is thus completed and the pre-stripped cathode plate 11Cp may be removed from the pre-stripping apparatus 40 and driven to the stripping apparatus 50 and a new coated cathode plate may be brought into the pre-stripping position.

The pre-strip cycle cannot be longer than the strip cycle without step (C) as depicted in fig. 2 (compare fig. 1 (with step (C)) and fig. 2 (without step (C)) in order to avoid the pre-strip operation becoming a bottleneck in the production line, increasing instead of decreasing the entire strip cycle. Thus, the pre-peel cycle has a duration preferably less than 6.5s, more preferably less than 6s, and most preferably less than 5 s. For example, for both embodiments of fig. 4 and 5, the entire pre-stripping operation may last between 3s and 5 s.

Preferably, at the pre-peel position, the distance Δ between the layer upper edge 13u and the tip of the blade module 22 is no more than 50% of the layer height H13 (i.e., Δ+.50H13), preferably no more than 30% (i.e., Δ+.30H13), more preferably no more than 20% (i.e., Δ+.20H13). The distance delta is preferably at least 5% (i.e. delta. Gtoreq.5% H13) of the layer height H13, preferably at least 10% (i.e. delta. Gtoreq.10% H13), more preferably at least 15% (i.e. delta. Gtoreq.5% H13). The distance delta is preferably comprised between 150mm and 300mm (i.e. delta = 150mm to 300 mm).

Blade module 21

As explained above, the blade module 21 is provided with two blades 22, the two blades 22 being positioned on either side of the operating plane and forming the tip of the blade module and being configured for movement between:

standby configuration, characterized as: the standby distance d0 between the blades being greater than the thickness of the cathode edge 11r, allowing the blade module to be moved from the standby position to the starting position, and

a pre-peel configuration characterized as: the pre-strip distance is less than the standby distance (d 1< d 0) and is included between the cathode plate thickness and the coated plate thickness.

The pre-strip distance d1 is preferably no more than 20% of the thickness of the cathode plate (excluding the cathode rim thickness), more preferably no more than 10% of the thickness of the cathode plate, and most preferably no more than 5% of the thickness of the cathode plate. In a preferred embodiment, the two blades contact the first and second major surfaces in a pre-stripping configuration, wherein the pre-stripping distance d1 is substantially equal to the cathode plate thickness.

In the embodiment illustrated in fig. 6, the blade module 21 includes a blade module frame 21f, the blade module frame 21f including a first branch and a second branch separated by a gap. It also comprises a first and a second elongated jaw 21a. Each elongated jaw includes a drive end and a blade end opposite the drive end and is rotatably coupled to the first and second branches with a jaw hinge spaced from the drive end and the blade end. The blade end of each of the first and second elongated jaws is provided with a blade 22.

The blade module further comprises a clamping actuator 21p selected from hydraulic, pneumatic or electric pistons, which clamping actuator 21p comprises a cylinder fixed to the blade module frame 21f and a piston fixed to the clamping mechanism. The clamping mechanism includes first and second beams 21b, each beam including a first end rotatably coupled to a free end of a piston of the clamping actuator, and a second end rotatably coupled to a drive end of a corresponding elongated jaw 21a. As shown in fig. 6 (a) and 6 (b), the piston translates a closing distance δ relative to the cylinder of the clamping actuator 21p, driving the pivoting of the first and second elongated jaws about the respective jaw hinges, and thus moving the blade 22 between the standby configuration and the pre-peeling configuration.

The blade module may be blocked into the pre-peel configuration by designing the module such that the first and second beams 21b form an angle comprised between 160 ° and 180 ° when the blade 22 is in the pre-peel configuration. This is illustrated in fig. 6 (b) and 6 (c), wherein the first beam and the second beam 21b are substantially parallel and collinear. With this configuration, it is almost impossible to drive the blades apart from each other by applying a force at the level of the blades. The only way to drive the blades apart is to raise the piston relative to the cylinder of the clamping actuator. The stability of the blade module in the pre-peel configuration contributes to the repeatability of the pre-peel operation, as it is not possible to force one or the other blade away from the interface between the metal layer and the corresponding major surface.

In a second embodiment illustrated in fig. 7, the blade module 21 includes a blade module frame 21f, the blade module frame 21f including first and second branches separated by a gap and first and second elongated jaws 21a similar to the embodiment of fig. 6. Each elongated jaw includes a drive end and a blade end opposite the drive end, and is rotatably coupled to the first and second branches with a jaw hinge spaced from the drive end and the blade end, the blade end of each of the first and second elongated jaws being provided with a blade 22.

The embodiment of fig. 7 differs from the embodiment of fig. 6 in that it includes a clamping actuator system comprising:

a first and a second clamping actuator 21p selected from hydraulic, pneumatic or electric pistons, the first and second clamping actuators 21p comprising a cylinder fixed to the blade module frame 21f and a piston coaxially arranged and facing away from each other, each clamping actuator comprising a cylinder fixed to the blade module frame 21f and a piston having a free end coupled to the driving end of the corresponding elongated jaw 21a, or

A double-acting clamping actuator 21p selected from double-acting hydraulic, pneumatic or electric pistons, the double-acting clamping actuator 21p comprising a cylinder fixed to the blade module frame 21f and two spaced-apart pistons coaxially arranged and having free ends facing away from each other, the free end of each of the two spaced-apart pistons being coupled to the driving end of a corresponding elongated jaw 21 a.

As illustrated in fig. 7 (a) and 7 (b), the piston translates a closing distance relative to the cylinder of the clamping actuator system, driving the pivoting of the first and second elongated jaws 21a about the respective jaw hinges, and thus moving the blade 22 between the standby configuration and the pre-peeling configuration.

The pressure in the first and second clamping actuators or the pressure in the double acting clamping actuator is typically sufficient to ensure stability of the blade module in the pre-stripping configuration. If greater stability is desired, the blade module may be provided with a locking system that is actuated to block the position of the piston relative to the cylinder of the clamp actuator when the blade module is in the pre-peeling configuration.

The blade modules 21 preferably have a thickness (D0, D1) measured parallel to the longitudinal axis X1 that is less than the distance separating every other cathode plate arranged on the conveyor. In this way, the conveyor 29 can simply pass through the opening defined by the frame without any decoupling mechanism (uncoupling mechanism) for carrying the individual cathode plates out of the conveyor for pre-stripping.

Method for stripping electrodeposited target metal layer from cathode plate

The invention also relates to a method for stripping an electrodeposited target metal layer on a first and a second surface of a cathode plate 11C by means of an electrolytic deposition process, comprising the following steps, schematically illustrated in fig. 3.

An electrowinning line as described above is provided and the cathode plate 11C coated with a layer of target metal 13 on the first and second major surfaces can be transferred from the electrolytic cell 1 to a conveyor 29 for conveying them one at a time to pre-stripping locations within the opening of the frame 40f of the pre-stripping apparatus 40. The cathode plate 11C may be blocked at the pre-strip location to prevent it from moving during the pre-strip operation. Starting from the layer upper edge 13u, a crack is initiated between each of the first and second main surfaces of the cathode plate and the corresponding target metal layer to form a pre-stripped cathode plate 11Cp.

The pre-stripped cathode plate 11Cp is conveyed to a stripping location within the opening of the frame of the stripping apparatus 50, and the target metal layer is stripped from the first and second major surfaces of the pre-stripped cathode plate 11Cp and recovered.

Crack initiation is performed by the pre-peeling apparatus as follows. When the cathode plate is transferred to the pre-strip zone, the pre-strip arm is in the standby position and the blade module 21 is in the standby configuration.

Once the cathode plate is at the pre-stripping zone, the pre-stripping arm 21 is moved from the standby position to the start position. During this movement, the blades of the blade module do not interfere with and pass through either side of the cathode edge 11r, because the standby distance d0 of the blades from each other is greater than the thickness of the cathode edge measured parallel to the longitudinal axis X1.

At the start position, the blade module is brought from the standby configuration to the pre-peeling configuration by decreasing the distance between the blades from the standby distance d0 to the pre-peeling distance d 1. By extending the length of the pre-peel arm by a length d, from the contact length Lc to a pre-peel length L1 that is greater than the contact length (i.e.,) The blade module is moved from the starting position to the pre-peeling position in the pre-peeling configuration to insert the blades of the blade module and create an initial delamination area between the metal layer and the corresponding first and second major surfaces at the level of a portion of the layer upper edge 13 u. The initial delamination area does not extend far enough across the width W of the metal layer and will not be sufficient for safely performing a subsequent lift-off operation.

The pre-stripping arm 20 is rotated about the hinge 20h until the tip of the blade module 21 is located between the cathode edge 11r and the layer upper edge 13u of the metal layer so as to extend the initial delamination area to a substantial portion of the layer upper edge 13u and preferably the entire width W of the layer upper edge 13 u.

At this stage, the blade module is brought back to the standby configuration by increasing the distance between the blades from the pre-peel distance d1 to the standby distance d 0. Thus, the pre-peel arm may be moved back to the standby position. During this movement, the blades of the blade module do not interfere with and pass either side of the cathode edge 11r, because the standby distance d0 of the blades from each other is greater than the thickness of the cathode edge 11 r.

In a preferred embodiment, the pre-peeling apparatus is of the type depicted in fig. 4, wherein in the standby position, the pre-peeling arm 20 has a contact length Lc and forms a standby angle greater than zero with the vertical direction (i.e., parallel to axis Z) at the level of the hinge 20 h. As shown in fig. 4 (b), the pre-peeling arm can be moved from the standby position to the start position by merely rotating the pre-peeling arm, thus reducing the angle formed with the vertical direction at the horizontal plane of the hinge from the standby angle to a start angle (preferably zero) smaller than the standby angle. During rotation, the length of the pre-peel arm does not change and the contact length Lc is maintained. The start angle is preferably zero such that the pre-peel arm is vertical when in the start position.

As described above, the initiation and formation of the crack is performed by a combination of translational and rotational movement of the pre-peeling arm to initiate and propagate the first crack along the width of the layer upper edge 13 u. After the formation of the crack is completed, the pre-peeling arm may return to its standby position at the end of rotation for propagating the crack. The length of the pre-peel arm decreases from the pre-peel length L1 to the contact length Lc.

In an alternative embodiment, the pre-stripping apparatus is of the type depicted in fig. 5, wherein in the standby position, the pre-stripping arm 20 has a standby length L0 and is vertical (i.e., parallel to axis Z). As shown in fig. 5 (b), the pre-peeling arm can be moved from the standby position to the start position only by stretching the pre-peeling arm from the standby length L0 to the contact length Lc (i.e., L0< Lc). The pre-peel arm maintains its vertical orientation during elongation.

As explained above, at the end of the rotation for propagating the crack, the pre-peel arm may be returned to its standby position by first reducing the length of the pre-peel arm from the pre-peel length L1 to the standby length L0 (where L0< Lc < L1), and rotating the pre-peel arm back to a vertical orientation (not shown).

With the present method, the peeling cycle can easily be less than 8 seconds, preferably less than 7 seconds, and yields a peeling rate of more than 470 pl/h, preferably more than 500 pl/h, more preferably more than 550 pl/h.

In the event that the adhesion between the metal layer and the major surface of the cathode plate is so strong that the force required to move the pre-peel arm for the blade module in the pre-peel configuration from the start position to the pre-peel position exceeds the threshold force value by extending the length of the extendable arm portion 20b relative to the main arm portion 20a, a safety procedure is initiated that includes the steps of:

In case the force exceeds the threshold force value again, the safety program can be run again and after a predetermined number of repetitions the plate has to be discarded as defective and non-peelable.

Advantages of the present electrolytic deposition production line

The electrolytic deposition line of the present invention can reliably improve the productivity of the peeled metal layer by more than 25%. This may be achieved by using a pre-stripping apparatus as described above. The novel concept of the pre-peeling apparatus improves reproducibility of the pre-peeling operation, allowing the productivity to be improved by more than 25% compared to the prior art pre-peeling apparatus for the following reasons.

As illustrated in fig. 4 and 5, the pre-stripping apparatus of the present invention initiates a first crack on a limited interface area by a first translational movement of the blade along the interfaces between the first and second major surfaces and the corresponding metal layers. The limited area of the first crack is due to the use of a blade that is much smaller than the width W of the metal layer measured parallel to the axis Y1. This has the advantage that for a given force applied by the blade to the corresponding interface, the stress thus created is very high and in almost all cases higher than the interfacial adhesion strength between the first and second main surfaces and the corresponding metal layer. This ensures an almost fault-free formation of the first crack (quasi failure free formation). The first crack must extend along the width of the upper edge of the layer to facilitate the stripping operation in a stripping apparatus positioned downstream of the pre-stripping apparatus.

The propagation of the first crack is performed by rotation of the pre-stripping arm about the arm hinge 20h, thus sliding the blade (swiping) between the first and second main surfaces and the corresponding metal layer along the plane defined by the cathode plate and perpendicular to the longitudinal axis X1. The circular sliding of the blade causes the first crack to extend along the entire width of the metal layer and drives the pre-stripping arm over the cathode plate for quick and easy return to the standby position ready to receive a new cathode plate.

The combination of translational and rotational movement of the small-sized blade with respect to the width W of the metal layer produces:

high reproducibility of the formation of pre-cracks between the first and second main surfaces and the corresponding metal layer, and

high rate of pre-strip cycles.

Both of these effects are critical to successfully reducing the peel cycle time by more than 25% relative to a process that does not include pre-peel equipment.

The pre-stripping apparatus defined in the present invention can be integrated in existing stripping lines without difficulty by integrating the pre-stripping apparatus defined in the present invention upstream of the stripping apparatus without a prior pre-stripping apparatus in the upstream of the stripping apparatus, or by replacing an existing prior art pre-stripping apparatus with a pre-stripping apparatus according to the present invention.

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The application also provides the following aspects:

1) An electrowinning line for recovering a target metal (13) electrolytically coated on a cathode plate (11C), the electrowinning line comprising:

-a plurality of cathode plates (11C), the plurality of cathode plates (11C) comprising a first main surface and a second main surface separated by a cathode plate thickness and delimited by a perimeter having an upper edge provided with a cathode rim (11 r) and a lower edge (11 d) opposite to the upper edge, both the first main surface and the second main surface being coated with a metal layer of a target metal (13), the metal layer of the target metal (13) extending over a layer height (H13) measured between the lower edge (11 d) and a layer upper edge (13 u) of the metal layer and delimiting a coated plate thickness,

-a conveyor (29), the conveyor (29) extending along a longitudinal axis (X1), being configured for holding the cathode plate vertically with the cathode edge (11 r) positioned upwards, and for conveying the cathode plate (11C) with the first and second main surfaces perpendicular to the longitudinal axis (X1), first

o transferring the cathode plate to a pre-stripping zone within an opening of a frame (40 f) of a pre-stripping apparatus (40), the pre-stripping apparatus (40) defining an operating plane perpendicular to the longitudinal axis (X1) and being configured parallel to the cathode plate for initiating a crack between each of the first and second main surfaces of the cathode plate and an upper edge of a layer of the target metal to form a pre-stripped cathode plate (11 Cp), and

One-step ground

o transferring the cathode plate to a stripping location within an opening of a frame of a stripping apparatus (50), the stripping apparatus (50) being configured for stripping and recovering the stripped target metal layer from the first and second main surfaces of the pre-stripped cathode plate (11 Cp),

characterized in that the pre-stripping device (40):

comprises a pre-stripping arm (20), said pre-stripping arm (20)

o has a degree of freedom parallel to the operating plane and rotating about a hinge (20 h) coupled to the frame (40 f), the rotation of the pre-stripping arm about the hinge being driven by a tilt actuator (27), and

o has an axial degree of freedom allowing a variation of the length of the pre-stripping arm comprised between the hinge and the tip of the blade module (21) at the first free end of the pre-stripping arm, said variation of the length being driven by a length actuator selected from hydraulic, pneumatic or electric pistons,

wherein the tilt actuator and the length actuator are configured for moving the pre-peel arm between:

o a standby position in which the pre-stripping arm does not interfere with the transport of the cathode plate (11C),

o a start position in which the tip of the blade module is in a position relative to the cathode plate (11C) at the pre-strip zone, the position being comprised between the cathode edge (11 r) and the layer upper edge (13 u) of the metal layer, and

o a pre-stripping position in which the tips of the blade modules are in a position relative to a cathode plate (11C) positioned at the pre-stripping zone, the position being comprised between the layer upper edge (13 u) of the metal layer and the lower edge (11 d) of the cathode plate,

-wherein the blade module (21) is provided with two blades (22), the two blades (22) being positioned on either side of the operating plane and forming the tip of the blade module and being configured for movement between:

o standby configuration, characterized in that the standby distance (d 0) between the blades is greater than the thickness of the cathode edge (11 r), allowing the pre-stripping arm to be moved from the standby position to the starting position, and

o pre-strip arrangement, characterized in that a pre-strip distance (d 1) is smaller than the standby distance (d 1< d 0) and comprised between the cathode plate thickness and the coated plate thickness.

2) The electrowinning line of claim 1), wherein the tilt actuator is selected from hydraulic, pneumatic or electric pistons, comprising a first end coupled to the frame (40 f) and a second end coupled to a second free end of the pre-stripping arm, the second free end being opposite the tip of the blade module and spaced from the tip of the blade module by the hinge (20 h).

3) The electrowinning line of 1), wherein the blade module (21) comprises,

a blade module frame (21 f), said blade module frame (21 f) comprising a first branch and a second branch separated by a gap,

first and second elongated jaws (21 a), each elongated jaw comprising a drive end and a blade end opposite the drive end and being rotatably coupled to the first and second branches with a jaw hinge spaced from the drive end and blade end, the blade end of each of the first and second elongated jaws being provided with a blade (22),

-a clamping actuator (21 p), the clamping actuator (21 p) being selected from hydraulic, pneumatic or electric pistons, the clamping actuator (21 p) comprising a cylinder fixed to the blade module frame (21 f) and a piston fixed to a clamping mechanism comprising,

-first and second beams (21 b), each comprising a first end rotatably coupled to a free end of the piston of the clamping actuator and a second end rotatably coupled to the driving end of a corresponding elongated jaw (21 a), such that the piston translates a closing distance (δ) with respect to the cylinder of the clamping actuator (21 p), driving the pivoting of the first and second elongated jaws about respective jaw hinges and thus moving the blade (22) between the standby configuration and the pre-peeling configuration.

4) The electrowinning line of claim 3), wherein the first and second beams (21 b) form an angle comprised between 160 ° and 180 ° when the blade (22) is in the pre-stripping configuration.

5) The electrowinning line of 1), wherein the blade module (21) comprises,

A clamping actuator system, said clamping actuator system comprising,

o a first and a second clamping actuator (21 p), the first and the second clamping actuator (21 p) being selected from hydraulic, pneumatic or electric pistons, the first and the second clamping actuator (21 p) comprising a cylinder fixed to the blade module frame (21 f) and a piston coaxially arranged and facing away from each other, each clamping actuator comprising a cylinder fixed to the blade module frame (21 f) and a piston having a free end coupled to the driving end of the corresponding elongated jaw (21 a), or

o a double acting clamping actuator (21 p), the double acting clamping actuator (21 p) being selected from double acting hydraulic, pneumatic or electric pistons, the double acting clamping actuator (21 p) comprising a cylinder fixed to the blade module frame (21 f) and two spaced pistons coaxially arranged and having free ends facing away from each other, the free end of each of the two spaced pistons being coupled to the driving end of a corresponding elongated jaw (21 a),

translating the piston a closing distance relative to the cylinder of the clamping actuator system, driving the pivoting of the first and second elongated jaws (21 a) about respective jaw hinges, and thus moving the blade (22) between the standby configuration and the pre-peeling configuration.

6) The electrowinning line of 1), wherein the pre-stripping apparatus includes a blocking element for securing the cathode plate at the pre-stripping location.

7) The electrowinning line of claim 1), wherein the blade modules (21) have a thickness (D0, D1) measured parallel to the longitudinal axis (X1), the thickness of the blade modules (21) being less than twice the distance separating two adjacent cathode plates arranged on the conveyor.

8) The electrowinning line of 1), wherein at the pre-stripping position the distance (delta) between the layer upper edge (13 u) and the tip of the blade module (22) does not exceed 50% of the layer height (H13) (i.e. delta. Ltoreq.50% H13).

9) The electrowinning line of 8), wherein at the pre-stripping position the distance (Δ) between the layer upper edge (13 u) and the tip of the blade module (22) is comprised between 150mm and 300mm (i.e. Δ = 150mm to 300 mm).

10 The electrowinning line of 1), wherein the target metal is selected from zinc, copper, nickel or gold.

11 A method for stripping an electrodeposited target metal layer on a first surface and a second surface of a cathode plate (11C) by an electrodeposition process, the method comprising the steps of:

Providing an electrowinning line according to 1),

transporting the cathode plate (11C) coated with a layer of target metal (13) on the first and second main surfaces to the pre-stripping zone within the opening of the frame (40 f) of the pre-stripping apparatus (40),

initiating a crack between each of the first and second main surfaces of the cathode plate and the layer of the corresponding target metal, starting from the layer upper edge (13 u), to form a pre-stripped cathode plate (11 Cp),

transporting the pre-stripped cathode plate (11 Cp) to the stripping position within the opening of the frame of the stripping apparatus (50),

stripping the layer of target metal from the first and second main surfaces of the pre-stripped cathode plate (11 Cp) and recovering the stripped target metal layer,

characterized in that the step of initiating the crack is performed as follows:

when the cathode plate is transferred to the pre-stripping station, the pre-stripping arm is in the standby position and the blade module (21) is in the standby configuration,

once the cathode plate is in the pre-stripping zone, the pre-stripping arm (21) is moved from the standby position to the starting position,

At the start position, by reducing the distance between the blades from the standby distance (d 0) to the pre-peeling distance (d 1), the blade module is brought to the pre-peeling configuration,

by extending the length of the pre-stripping arm from a starting length (Lc) to a pre-stripping length (L1) that is greater than the starting length (Lc < L1), the blade module is moved from the starting position to the pre-stripping position in the pre-stripping configuration to insert the blade of the blade module between the metal layer and the corresponding first and second main surfaces, creating an initial delamination area at the level of a portion of the layer upper edge (13 u),

-rotating the pre-stripping arm (20) about the hinge (20 h) until the tip of the blade module (21) is located between the cathode edge (11 r) and the layer upper edge (13 u) of the metal layer, so as to extend the initial delamination area to a substantial part of the layer upper edge (13 u), and preferably the entire width (W) of the layer upper edge (13 u), followed by

Bringing the blade module to the standby configuration by increasing the distance between the blades from the pre-peel distance (d 1) to the standby distance (d 0), and

-moving the pre-peel arm back to the standby position.

12 The method according to 11), wherein

In the standby position, the pre-stripping arm (20) has the contact length (Lc) and forms a standby angle greater than zero with the vertical direction at the level of the hinge (20 h), and

the movement of the pre-stripping arm from the standby position to the starting position is performed by rotating the pre-stripping arm to reduce the angle formed with the perpendicular direction at the horizontal plane of the hinge from the standby angle to a starting angle smaller than the standby angle, preferably the starting angle is zero.

13 The method according to 11), wherein

In the standby position, the pre-peeling arm (20) has a standby length (L0) smaller than the start length (Lc) and forms a standby angle of zero with the vertical direction at the level of the hinge (20 h), and

-performing a movement of the pre-stripping arm from the standby position to the starting position by increasing the length of the pre-stripping arm from the standby length (L0) to the starting length (Lc) while keeping the standby angle at zero constant.

14 The method according to 11), wherein if the force required to move the pre-peel arm from the start position to the pre-peel position by extending the length of the pre-peel arm exceeds a threshold force value, a safety procedure is initiated, the safety procedure comprising the steps of:

by increasing the distance between the blades from the pre-peel distance (d 1) to the standby distance (d 0), then by bringing the pre-peel arm to the starting position, the blade module is brought to the standby configuration,

at the start position, the blade module is brought to the pre-peeling configuration by reducing the distance between the blades from the standby distance (d 0) to the pre-peeling distance (d 1), and

-by extending the length of the pre-peel arm from the starting length (Lc) to the pre-peel length (L1), the blade module is moved again from the starting position to the pre-peel position in the pre-peel configuration.

15 The method according to 11), wherein the cycle time for performing all steps of the method is less than 8 seconds.

16 A pre-stripping apparatus (40) for use in an electrowinning line according to 1), comprising:

-a frame (40 f), said frame (40 f) comprising an opening defining a pre-peeling zone comprised in an operating plane perpendicular to a longitudinal axis (X1),

a pre-stripping arm (20),

Claims

1. An electrowinning line for recovering a target metal (13) electrolytically coated on a cathode plate (11C), the electrowinning line comprising:

o transferring the cathode plate to a pre-stripping zone within an opening of a frame (40 f) of a pre-stripping apparatus (40), the pre-stripping apparatus (40) defining an operating plane perpendicular to the longitudinal axis (X1) and being configured parallel to the cathode plate for initiating a crack between each of the first and second main surfaces of the cathode plate and an upper edge of a metal layer of the target metal to form a pre-stripped cathode plate (11 Cp), and further

o transporting the cathode plate to a stripping location within an opening of a frame of a stripping apparatus (50), the stripping apparatus (50) being configured for stripping and recovering the metal layer of target metal stripped from the first and second main surfaces of the pre-stripped cathode plate (11 Cp),

characterized in that the pre-stripping device (40):

-comprising a pre-stripping arm (20), said pre-stripping arm (20):

o has a degree of freedom parallel to the operating plane and rotating about a hinge (20 h) coupled to the frame (40 f) of the pre-peeling apparatus, the rotation of the pre-peeling arm about the hinge being driven by a tilt actuator (27), and

o a pre-stripping position in which the tips of the blade modules are in such a position with respect to a cathode plate (11C) positioned at the pre-stripping zone,

this position is comprised between the layer upper edge (13 u) of the metal layer and the lower edge (11 d) of the cathode plate,

o standby configuration, characterized by: a standby distance (d 0) between the blades being greater than the thickness of the cathode edge (11 r), allowing the pre-stripping arm to be moved from the standby position to the starting position, and

o pre-peel configuration, characterized by: a pre-strip distance (d 1) is less than the standby distance (d 1< d 0) and is included between the cathode plate thickness and the coated plate thickness.

2. The electrowinning line of claim 1 wherein the tilt actuator is selected from hydraulic, pneumatic or electric pistons, including a first end coupled to the frame (40 f) of the pre-stripping apparatus and a second end coupled to a second free end of the pre-stripping arm, the second free end being opposite the tip of the blade module and spaced from the tip of the blade module by the hinge (20 h).

3. The electrowinning line as claimed in claim 1, wherein said blade modules (21) comprise,

-a clamping actuator (21 p), the clamping actuator (21 p) being selected from hydraulic, pneumatic or electric pistons, the clamping actuator (21 p) comprising a cylinder fixed to the blade module frame (21 f) and a piston fixed to a clamping mechanism comprising:

4. An electrowinning line as claimed in claim 3, wherein said first and second beams (21 b) form an angle comprised between 160 ° and 180 ° when said blade (22) is in said pre-stripping configuration.

5. The electrowinning line as claimed in claim 1, wherein said blade modules (21) comprise,

a clamping actuator system, the clamping actuator system comprising:

6. The electrowinning line of claim 1 wherein the pre-stripping apparatus includes a blocking element for securing the cathode plate at the pre-stripping location.

7. An electrowinning line according to claim 1, wherein said blade modules (21) have a thickness (D0, D1) measured parallel to said longitudinal axis (X1), said thickness of said blade modules (21) being less than twice the distance separating two adjacent cathode plates arranged on said conveyor.

8. The electrowinning line of claim 1 wherein at the pre-stripping position the distance (Δ) between the layer upper edge (13 u) and the tip of the blade module (21) is no more than 50% of the layer height (H13).

9. The electrowinning line of claim 8 wherein at the pre-stripping position the distance (Δ) between the layer upper edge (13 u) and the tip of the blade module (21) is comprised between 150mm and 300 mm.

10. The electrowinning line of claim 1 wherein the target metal is selected from zinc, copper, nickel or gold.

11. A method for stripping a metal layer of a target metal electrodeposited on a first surface and a second surface of a cathode plate (11C) by an electrodeposition process, the method comprising the steps of:

providing an electrowinning line according to any one of claims 1 to 10,

transferring the cathode plate (11C) coated with a metal layer of a target metal (13) on the first and second main surfaces to the pre-stripping zone within the opening of the frame (40 f) of the pre-stripping apparatus (40),

initiating a crack between each of the first and second main surfaces of the cathode plate and the metal layer of the corresponding target metal, starting from the layer upper edge (13 u), to form a pre-stripped cathode plate (11 Cp),

Transferring the pre-stripped cathode plate (11 Cp) to the stripping zone within the opening of the frame of the stripping apparatus (50),

stripping the metal layer of the target metal from the first and second main surfaces of the pre-stripped cathode plate (11 Cp) and recovering the stripped metal layer of the target metal,

characterized in that the step of initiating the crack is performed as follows:

once the cathode plate is in the pre-stripping zone, the pre-stripping arm (20) is moved from the standby position to the starting position,

-rotating the pre-stripping arm (20) about the hinge (20 h) until the tip of the blade module (21) is located between the cathode edge (11 r) and the layer upper edge (13 u) of the metal layer, so as to extend the initial delamination area to a substantial part of the layer upper edge (13 u), then

-moving the pre-peel arm back to the standby position.

12. The method according to claim 11, wherein the pre-stripping arm (20) is rotated about the hinge (20 h) until the tip of the blade module (21) is located between the cathode rim (11 r) and the layer upper edge (13 u) of the metal layer so as to extend the initial delamination area to the full width (W) of the layer upper edge (13 u).

13. The method according to claim 11 or 12, wherein

In the standby position, the pre-stripping arm (20) has a contact length (Lc) and forms a standby angle greater than zero with the vertical direction at the level of the hinge (20 h), and

the movement of the pre-peeling arm from the standby position to the start position is performed by rotating the pre-peeling arm to reduce the angle formed with the vertical direction at the horizontal plane of the hinge from the standby angle to a start angle smaller than the standby angle.

14. The method of claim 13, wherein the start angle is zero.

15. The method according to claim 11 or 12, wherein

16. The method of claim 11 or 12, wherein if the force required to move the pre-peel arm from the starting position to the pre-peel position by extending the length of the pre-peel arm exceeds a threshold force value, a safety procedure is initiated, the safety procedure comprising the steps of:

17. The method of claim 11 or 12, wherein the cycle time for performing all steps of the method is less than 8 seconds.

18. Pre-stripping apparatus (40) for use in an electrowinning line in accordance with any one of claims 1 to 10, comprising:

-a pre-stripping arm (20), the pre-stripping arm (20):