EP3470550B1

EP3470550B1 - Electrode head for an electrolysis installation

Info

Publication number: EP3470550B1
Application number: EP16891321.8A
Authority: EP
Inventors: Yves Lefevre
Original assignee: Zincobre Ingenieria SL
Current assignee: Zincobre Ingenieria SL
Priority date: 2016-02-24
Filing date: 2016-02-24
Publication date: 2023-10-25
Anticipated expiration: 2036-02-24
Also published as: RU2712167C1; EP3470550C0; WO2017144737A1; EP3470550A1; EP3470550A4; RU2712167C9; MX2017000940A

Description

TECHNICAL FIELD AND OBJECT OF THE INVENTION

Electrolysis installations include electrolysis cells with pairs of electrodes, cathode and anode, and a tank with a solution in which the electrodes are submerged subjected under a continuous electrical voltage difference in order to produce electrolysis. Electrolysis enables obtaining for example zinc, copper, nickel cadmium or cobalt deposited in the cathode from the salts of the solution.
Unlike electrolysis processes through electrorefining, in electrowinning the anode is substantially insoluble during electrolysis, providing the surface for producing the anodic oxidation reaction. These processes conventionally use a lead anode but other types of alloys such as titanium can be used.
Conventionally, electrodes are plate-shaped, arranged in rows in the tank such that the anodes and cathodes alternate and the cells are connected electrically in series. For the electrical connection between the electrodes during electrolysis, an electrode head holds each electrode. The electrode head comprises an electrode rod of an electrically conductive material, usually copper, and during electrolysis, the electrode head holds the electrode in the tank, vertically and in the longitudinal direction of the rod. Likewise, each rod is arranged abutting in electrical contact on equipotential rails, usually made of copper, that extend to the sides of the tank and perpendicularly to the electrodes. An electrode unit comprises an assembly of the electrode and the electrode head. The electrode units are positioned in the tank as close as possible to each other in order to increase the productivity of the installation, but avoiding the risk of a short circuit. The electrode head comprises handling means for facilitating the extraction or the insertion of the electrode in the tank, or the transport thereof by means of a crane or a bridge crane of the installation, for example in the form of hooks or gripping lugs. Patent EP 1492906 discloses this type of arrangement in an electrolysis installation.
The present invent relates to an electrode head for an electrolysis installation of the type described in the preceding paragraph. The invention is especially applicable to anodes of an electrolysis installation by electrowinning, specifically for zinc electrolysis.

BACKGROUND OF THE INVENTION

Patent application publication WO 2013/150163 describes an anode head for a zinc electrolysis installation. Conventionally and as described in this publication, the anode head comprises a coating on the electrolysis rod against acid mist corrosion, especially present in electrowinning, particularly in zinc electrowinning processes. This publication discloses handling means of the anode head made of composite material, and which are fixed to the electrolysis rod through press fittings. This anode head has the drawback that the fixing of the handling means of the anode head to the electrolysis rod requires additional fixing means such as an additional weld bead in order to ensure the fixing. However, the welding presents problems of stress concentration and vulnerability to corrosion that can cause the fixation to fail, for example, due to fatigue, since the electrode units are subjected to cycles of loading and unloading during the normal operation of the installation, for example, to collect the metal deposited in the cathodes in the electrowinning installations, or in maintenance operations of the electrode units, decreasing the productivity or the useful life of the installation.
Therefore, an object of the present invention is to provide an electrode head that provides a fixing of the handling means or other additional element to the electrolysis rod in a safe manner, especially without requiring additional fixing means such as welding.

DESCRIPTION OF THE INVENTION

The present invention provides an electrode head for an electrolysis installation as set forth in claim 1 and explained below. Furthermore, the dependent claims reflect advantageous embodiments as disclosed below.
The electrode head according to the invention comprises, unlike those known in the state of the art, a coating on the electrolysis rod with a varying thickness according to a longitudinal direction of the rod, said varying thickness for providing a stop or a shape adjustment of the handling means and/or of an additional element. The stop or shape adjustment provided by the varying thickness of the coating enables one-way or two-way fixation in the longitudinal direction of the electrolysis rod.
The invention enables secure fixing of the handling means as well as other additional elements that can provide additional technical features. These additional elements can be, for example, electrode state sensors, or RFID devices (radio frequency identification device), which make it possible to identify a specific electrode, thereby improving the traceability of the electrode in the installation.
By securing the fixing of the handling means and/or additional elements to the electrolysis rod, any movement of the handling means or of the additional elements is prevented or avoided without the need for additional fixing means. Likewise, the use of welding exposed to corrosion can be eliminated or reduced, thus decreasing or eliminating the risk of failure of the electrode units, for example, due to delamination of the electrode plate especially during handling or transport of the electrode units, and therefore lengthening the useful life of the installation. The more secure fixing implies a safer and more reliable operation of the installation during the handling or transport process of the electrode units.
On the other hand, the invention also provides the advantage of enabling the fixing of several types of handling means, including those that are removable, thus increasing the design possibilities of the electrolysis rod.
The present invention also anticipates that the coating has a varying thickness according to a transverse direction of the rod in order to provide a stop or a shape adjustment of the handling means and/or of an additional element, for example, by providing a cavity for the coating. This way, the fixing of the handling means or of the additional elements, such as an RFID, can be ensured to a greater extent.
The varying thickness can be obtained by molding or overmolding the rod and, optionally, subsequent machining of the thickness. Machining through numerical control enables adapting the thickness to the required adjustment tolerances.
The invention also anticipates that said shape adjustment provided by the coating of varying thickness be carried out with tightening, for example, by adjusting the shape or size perimeters of the elements that are to be fixed to each other, which also enables improving the security of the fixing.
The shape of the varying thickness will depend on the shape of the elements to be fixed and the type of fixing required, for example, if the fixing is removable. Particularly, the shape of the thickness can be configured to have a variable gradient, for example, according to the longitudinal or transverse direction of the rod.
Advantageously, the coating of varying thickness is configured to protect the rod against acid mist corrosion. In other words, the conventional coating can be used so that, with a varying thickness, it also carries out the function of fixing the handling means or the additional elements, which therefore enables material and cost savings of the electrode head, as the coating is used both to provide protection against corrosion of the electrolysis rod and to improve the fixings. Furthermore, the coating can also be weldable to the electrode, for example, by using the same material for the coating as for the electrode material.
Advantageously, the coating of varying thickness can extend, at least partially, between the rod and the handling means. This way, losses due to leakage of electrical current between the rod and the handling means or through gradients of electrical current density in the rod are eliminated, which would exist if the contact were direct or if welding were carried out directly between the rod and the handling means for fixing thereof, improving the useful life of the electrode unit as well as the productivity of the installation. Likewise, the need to electrically isolate the handling means is eliminated, thus improving the security of the installation.
The handling means are covered at least partially by the coating of varying thickness, which enables further improving the fixing, by increasing the surface that adjusts or retains the elements to be fixed. This can be obtained, for example, by overmolding the assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a perspective view of an exemplary embodiment of an electrode head according to the present invention.
Figure 2a is a transverse cross-sectional view of a second exemplary embodiment of a part of an electrode unit and respective electrode head according to the present invention.
Figure 2b is a transverse cross-sectional view of a third exemplary embodiment of a part of an electrode unit and respective electrode head according to the present invention.

DETAILED DESCRIPTION OF AN EMBODIMENT

Figure 1 shows an embodiment of an electrode head 1 of the invention, with two handling means 21 adjusted in the coating 13 of the electrode rod 11 and an additional element 31 in the center of the electrode head 1, which is a radio frequency identification device or RFID encapsulated in the coating 13.
The handling means are arranged one at each end of the electrode head 1 and they have an upper area in the shape of a protrusion 211 that extends according to a longitudinal direction of the rod 11 towards the outside thereof. These protrusions 211 serve as hooks for collecting the electrode unit by means of a crane or a bridge crane of the electrolysis installation.
In Figures 2a and 2b details of the transverse cross section of the electrode unit around the handling means 21 can be seen, showing two different embodiments of the invention. In Fig. 2a the coating 13 of varying thickness according to the longitudinal direction of the rod 11 extends between the handling means 21 and the rod 11. In Figure 2b, the coating 13 of varying thickness further extends, partially covering the handling means 21, that is, the handling means are embedded in the coating 13 of varying thickness.
The electrode 12 has the shape of a plate, for example, a lead anode that can be used in a zinc electrowinning installation.
The coating 13 extends over the entire surface of the rod 11 except in an area for contacting with the equipotential rails at the ends of the rod. The coating 13 can be made of the same material as the electrode, for example, of a lead alloy having the same composition as the lead anode. The coating 13 protects the rod 11 against acid mist corrosion and facilitates the passage of electrical current throughout the electrode plate 12. The electrode plate 12 can be secured to the coating 13 by means of welding between the coating 13 and the electrode plate 12.
The handling means 21 can be made of stainless steel of a common configuration.

Claims

Electrode head (1) for an electrolysis installation comprising: an electrode rod (11) to which an electrode (12) can be secured; and handling means (21, 211) of the electrode head (1) fixed to the electrode rod (11) for transporting the electrode head (1) secured to the electrode (12) by means of a crane of the installation; characterized in that it incorporates a coating (13) on the electrode rod (11) with a varying thickness according to a longitudinal direction of the electrode rod (11) to provide a stop or an adjustment of the handling means (21, 211) and optionally of an additional element (31);
wherein the adjustment of the handling means (21, 211) is carried out by embedding in the coating (13) of varying thickness;

and wherein the handling means (21, 211) are covered at least partially by the coating (13).
Electrode head (1) according to claim 1, characterized in that the coating (13) has a varying thickness according to a transversal direction of the electrode rod (11) to provide a stop or an adjustment of the handling means (21, 211) and optionally of the additional element (31).
Electrode head (1) according to one of claims 1 or 2, characterized in that the handling means (21, 211) and the coating (13) of varying thickness are fitted by means of adjustment.
Electrode head (1) according to one of claims 1 to 3, characterized in that the coating (13) is configured to protect the electrode rod (11) against acid mist corrosion.
Electrode head (1) according to one of claims 1 to 4, characterized in that the coating (13) extends at least partially between the electrode rod (11) and the handling means (21, 211).
Electrode head (1) according to one of claims 1 to 5, characterized in that the handling means (21, 211) are made of stainless steel.
Electrode head (1) according to claim 1, characterized in that the additional element (31) is a radio frequency identification device or RFID.
Electrode unit comprising: an electrode head (1), as defined in claims 1 to 7, and an electrode (12) secured to the electrode rod (11).