WO2013063644A2

WO2013063644A2 - Method of removing metal from a cathode

Info

Publication number: WO2013063644A2
Application number: PCT/AU2012/001333
Authority: WO
Inventors: Jason Robert Cerezo
Original assignee: Steelmore Holdings Pty Ltd
Priority date: 2011-10-31
Filing date: 2012-10-31
Publication date: 2013-05-10
Also published as: CA2854102A1; FI20145302L; CN104185695A; WO2013063644A3

Abstract

A method of separating an electrolytically deposited metal from a cathode plate is disclosed. The method includes the step of locating a magnetic device in operative proximity to a face of the cathode plate, the face of the cathode plate having electrolytically deposited metal disposed thereon. The method also includes the step of applying a magnetic field using the magnetic device to thereby separate the deposited metal from the face of the cathode plate.

Description

TITLE

"METHOD OF REMOVING METAL FROM A CATHODE"

FIELD OF THE INVENTION

The invention relates to a method for recovering metal. In particular, although not exclusively, the invention relates to a method of removing electrolytically deposited metal from a cathode.

BACKGROUND TO THE INVENTION

The electrolysis of metal ions contained in a solution to give a solid metal product is a well known technique for isolating relatively pure metals. This technique is typically used in the processing of Nickel, Cobalt, Copper and Zinc.

A solid cathode is placed into a metal ion solution and an electric current is applied to the cathode. Electro deposition of the metal onto the cathode then occurs. Periodically, the cathode and the attached metal product are removed from the solution. The solid metal product is then separated from the cathode and, ideally, the cathode is then reused.

Separation of the solid metal product from the cathode is usually undertaken by physical methods ranging from manual removal by a person with a crowbar to automatic stripping machines.

A method utilizing a stripping machine is disclosed in US 4,840,710.

In this method, the cathode is firstly flexed to cause a part of the deposited metal to separate from the cathode forming a gap. Then a wedge is inserted into the gap and forced between the deposited metal and the cathode to separate the deposited metal. Physical methods used to separate the deposited metal may cause damage to the cathode either by the action of crowbars, wedges, knives or the like or by flexing or hammering the cathode in order to loosen the deposited metal.

Particular difficulties are faced when separating electrolytically deposited cobalt from a cathode. Cathodes for use in cobalt recovery are often designed with isolated islands of conductive metal surrounded by a non-conductive material such as a paint or resin. Thus the cobalt is deposited as a multiplicity of discrete portions. The cobalt tends to be deposited such that nodules or amorphous shapes form rather than flat sheets similar to those formed in copper deposition.

Stripping of cobalt from the cathode therefore requires physical separation at a multiple of points on the cathode. Thus there are many points where damage to the cathode may easily occur, particularly damage to the non-conductive material. Damage to the non-conductive material can lead to metal deposits forming on the damaged areas, which may in turn lead to further damage of the non-conductive material. Thus, the cathodes become unusable and the non-conductive material must be removed and reapplied at regular intervals. The conductive metal of the cathode may also become damaged, which can allow impurities to collect on the cathode and become incorporated into the deposited metal. Repair of the conductive metal of the cathode may be expensive in terms of the repair itself and also the downtime required to perform the repair.

There are various issues associated with the processing of each of the metals mentioned earlier. OBJECT OF THE INVENTION

It is an object of the invention to overcome or at least alleviate one or more of the above problems and/or provide the consumer with a useful or commercial choice.

DISCLOSURE OF THE INVENTION

In one form, although it need not be the only or indeed the broadest form, the invention resides in an apparatus for separating electrolytically deposited metal from a cathode, said apparatus comprising a magnetic device moveable to a position in relation to the cathode whereby the magnetic device is capable of separating the deposited metal from the cathode.

Preferably, the magnetic device is an electromagnet.

In another form, the invention resides in a method of separating an electrolytically deposited metal from a cathode including the step of:

locating a magnetic field near a cathode having deposited metal thereon to separate the deposited metal from the cathode.

Preferably, the method may include one or more of the steps of: placing a cathode into an electrolytic cell containing metal ions in solution;

applying a current to the solution to reduce the metal ions to a metal deposited onto the cathode ;

removing the cathode from the electrolytic cell;

placing a magnetic device adjacent to the cathode such that the metal preferentially adheres to the magnetic device; and/or

removing the cathode. In a particulariy preferred embodiment of the method, the magnetic device is an electromagnet. After removing the cathode from the electromagnet, the magnetic field of the electromagnet is reversed or switched off such that the metal releases from the electromagnet.

In a further form, the invention resides in a method of separating an electrolytically deposited metal from a cathode plate, the method including the step of:

locating a magnetic device in operative proximity to a face of the cathode plate, the face of the cathode plate having electrolytically deposited metal disposed thereon; and

applying a magnetic field using the magnetic device to thereby separate the deposited metal from the face of the cathode plate.

Preferably, the magnetic device is in the form of an electromagnet and the step of applying the magnetic field involves applying a current to the electromagnet.

Suitably, the magnetic device is in the form of an electromagnet and the step of applying the magnetic field involves applying a relatively high current to the electromagnet for relatively short pulse times.

In a preferred form, the electromagnet is pulsed at least twice.

Preferably, the magnetic device is located in operative proximity to a first face of the cathode plate and a second magnetic device is located in operative proximity to a second face of the cathode plate prior to application of the magnetic field.

The step of applying the magnetic filed involves applying a magnetic field using the first magnetic device and applying a magnetic filed using the second magnetic device to thereby separate the deposited metal from the first face of the cathode plate and from the second face of the cathode plate.

In still a further form the invention reside in a method of separating an electrolytically deposited metal from a cathode plate, the method including the steps of:

placing a cathode into an electrolytic cell containing metal ions in solution;

applying a current to the solution to reduce the metal ions to a metal deposited onto the cathode;

removing the cathode from the electrolytic cell;

Further features of the present invention will become apparent from the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

To assist in understanding the invention and to enable a person skilled in the art to put the invention into practical effect preferred embodiments of the invention will be described by way of example only with reference to the accompanying drawings, wherein:

FIGs. 1A to 1C show the sequential separation of an electrolytically deposited metal from a cathode using a magnetic device according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A magnetic device 100 is used to strip electrolytically deposited metal 210 from a cathode 200, as shown in the schematic of FIG 1.

The magnetic device 100 may be of any shape or size, but is preferably about the same size and shape as the cathode 200. Alternatively, the magnetic device 100 may be smaller in size than the cathode 200 and, in operation, is movable to be located adjacent to all areas of the cathode 200 in turn. The magnetic device 100 may be suitable for hand-held or automatic operation.

The magnetic device 100 may be a permanent magnet or an electromagnet. Preferably the magnetic device 100 is an electromagnet such that the magnetic field may be switched off or the polarity reversed to allow adhered metal to be released. Alternatively, a permanent magnet may be positioned behind a surface such that the magnetic field generated by the permanent magnet adheres metal onto the surface. When the permanent magnet is removed from behind the surface, any metal adhering to the surface is released.

The strength of the magnetic field generated by the magnetic device 100 is selected to be sufficient to separate deposited metal from the cathode 200.

Electrolytic deposition of a metal onto a cathode 200 (process not shown) begins with the step of immersing the cathode 200 into an electrolytic cell containing a solution which includes dissolved metal ions. A current is applied to the solution via the cathode 200, and a corresponding anode, which electrolytically reduces the metal ions to deposit pure metal onto the cathode 200.

This process may be used to isolate and purify various metals, including cobalt, nickel, copper and zinc. The cathode 200 is manufactured from a conductive metal, frequently stainless steel, and may be masked by cover strips 220 on the edges. Alternatively, the cathode 200 may be divided into islands of conductive metal surrounded by a non-conductive material such that the deposited metal forms in portions rather than as a single sheet (not shown).

After a sufficient quantity of metal has been deposited on the cathode 200, it is removed from the electrolytic cell and moved to a stripping area.

When the cathode 200 is being stripped of the deposited metal 210, the cathode 200 is supported by an attached hanger bar 230, a supporting structure (not shown) or a combination thereof.

As shown in FIG 1A, the magnetic device 100 is positioned adjacent to the cathode 200 such that the cathode is in operative proximity to a magnetic filed generated by the magnetic device 100 such that the deposited metal 210 experience the force of the magnetic field generated by the magnetic device 100.

In circumstances where the cathode 200 is fitted with edge cover strips 220, the edge cover strips 220 project outwardly from the face of the cathode 200. In this case, the magnetic device 100 is prevented from contacting the deposited metal 210 or the cathode face 240. This provides the advantage that the magnetic device 100 is prevented from sticking to the cathode face 240.

In a preferred embodiment, two magnetic devices 100 are positioned, one adjacent to each face of the cathode 200.

When the magnetic device 100 is adjacent to the cathode 200, as shown in FIG 1B, and the magnetic field is activated, the deposited metal 210 moves from the cathode 200 and preferentially adheres to the magnetic device 100.

Optionally, the magnetic field of the magnetic device 100 is pulsed using a large current for relatively short pulse times in order to separate the deposited material from the cathode 200. Preferably, the magnetic device 100 is pulsed at least twice.

In this embodiment, the cathode 200 is located within a containment vessel or the like in order that the deposited metal may be collected.

In a preferred form, the magnetic device 100 is pulsed using a relatively high current of about 1 ,500,000 amps for relatively short pulse times of 45 ms in duration.

In a more preferred form, two magnetic devices 100 in the form of electromagnets are located within operative proximity of the cathode 200, on either side thereof, and each magnetic device 100 is pulsed using a current of about 1 ,500,000 amps in pulses of 45 ms.

Once the deposited metal 210 has adhered to the magnetic device 100, the cathode 200 is moved away from the magnetic device 100, as shown in FIG 1C. The polarity of the magnetic device 100 is then reversed or deactivated, such that the deposited metal is released from the magnetic device 100 and falls into a receiving hopper, onto a conveyor or the like (not shown).

Optionally, in some embodiments the deposited metal 210 transfers from the cathode 200 and deposits directly in containers or the like located to capture the deposited metal. In these embodiments, the deposited metal is not magnetically located on a face of the magnetic device 100.

The cathode stripping method of the invention does not require flexing of the cathode or any physical contact between the stripping device and the cathode. Thus no physical force is exerted onto the cathode 200 which could cause any damage to the cathode 200 and any non-conductive material that is present. This may reduce operating costs as the 'lifespan' of each cathode 200 may be greatly increased. That is, each cathode 200 can be reused many more times before needing to be resurfaced when compared to cathodes stripped by standard physical methods.

Removal of the deposited metal is quick and simple, and does not require a machine with many moving parts, compressed air or the like. The stripping operation as well as the stripped metal may be easily controlled, as the stripped metal remains adhered to the magnetic device until the magnet polarity is reversed.

Throughout the specification the aim has been to describe the invention without limiting the invention to any one embodiment or specific collection of features. Persons skilled in the relevant art may realize variations from the specific embodiments that will nonetheless fall within the scope of the invention. For example, either the cathode 200 is brought adjacent to the magnetic device 100 or the magnetic device 100 is brought to be adjacent to the cathode 200 for the stripping operation. It will be appreciated that various other changes and modifications may be made to the embodiment described without departing from the spirit and scope of the invention.

Claims

1. A method of separating an electrolytically deposited metal from a cathode plate, the method including the step of:

2. The method of claim 1 , wherein the magnetic device is in the form of an electromagnet and the step of applying the magnetic field involves applying a current to the electromagnet.

3. The method of claim , wherein the magnetic device is in the form of an electromagnet and the step of applying the magnetic field involves applying a relatively high current to the electromagnet for relatively short pulse times.

4. The method of claim 3, wherein the electromagnet is pulsed at least twice.

5. The method of claim 1 , wherein the magnetic device is located in operative proximity to a first face of the cathode plate and a second magnetic device is located in operative proximity to a second face of the cathode plate prior to application of the magnetic field.

6. The method of claim 5, wherein the step of applying the magnetic S filed involves applying a magnetic field using the first magnetic device and applying a magnetic filed using the second magnetic device to thereby separate the deposited metal from the first face of the cathode plate and from the second face of the cathode plate. 0 7. A method of separating an electrolytically deposited metal from a cathode plate, the method including the steps of:

placing a cathode into an electrolytic cell containing metal ions in solution;

applying a current to the solution to reduce the metal ions to a metal5 deposited onto the cathode;

removing the cathode from the electrolytic cell;

0 applying a magnetic field using the magnetic device to thereby separate the deposited metal from the face of the cathode plate.